Yeah, a handheld holoprojector would be sweet. Even better than a datapad, because the information could be displayed in your normal view of the bridge (without having to look down). Likewise with having access to detailed information on it like status of damage or repairs to specific points, a current detailed list of fighter and ground assets, etc. One thing, though; I think it should be a little bit heavier duty projector than the ones seen in TPM and AOTC. Those appeared to be little more than picture viewers and data storage, while this would need to be very functional, and IMO should be a little bigger to allow for a keyboard or whatnot.
However, I also think there should still be a large central map projected from the ceiling onto the bridge itself. I realize we've never seen this sort of thing on an ISD bridge (though there was one in ROTJ during the rebel briefing), but it seems like it would be the most efficient way to issue orders to other ships and to get an overall view of the battle. handheld projectors are good and all, but I see no reason to use one for map management if the ship itself can project a much larger and more detailed map.
Oh, hey! Idea just hit. --> have two maps, one projected over each crew pit. One map would display the local battlefield (in orbit around a single celestial body) and the other would show a system wide view. This would help immensely in coordinating multi-front attacks, or in quickly spotting and reacting to enemy reinforcements closeby. Again, yeah, I know we've never seen this on an ISD, but then again, we've never really seen an ISD in pitched battle either, so we can't say that they
don't have something like this.

The only time I can think of where they might have showed up was the scene where Admiral Piett shouts "Intensify forward firepower!" before having his bridge blown up. However, Piett didn't really seem to be commanding his forces at that point. He was just looking out the window, and could have had any projectors off.
Overall, maybe the handheld holoprojector would be most usefull as a means of getting detailed information about your own ship and as a secondary means of viewing the surrounding battefield (perhaps from a different angle or level of zoom than the main projector).
I also like the idea of number keys snapping your view around to focus on a specific officer, then maybe further using the number keys to enter submenus and choose commands(BackSpace to back out of the menus or ESC to drop them alltogether and respond to some other threat). This would be a great substitute for the mouse-driven menu system I outlined earlier, and would actually be faster too, once you learned to use it.
So, at the end of it all, here's my vision for command and control in this game. Ahem....
General walking around would be controled by the mouse and standard WSAD controls. You could walk around the bridge pretty much wherever you want (you're the captain after all), and wherever you get the best view for the moment.
Two main ceiling mounted holoprojectors would give a view of the local battlefield and system wide view, respectively. The zooms and viewing angles could be controled wth the mouse by pressing CTRL or SHIFT respectively to access each projector, then using a Homeworld style mouse camera control to adjust the view.
The local map would reflect the friendly and enemy selections made by the player (discussed more later) and the locations of goals and nav. points. Ships would likely be represented by icons or low-poly models (see reason below). Their names and the other ships in their batle line woud be shown upon selection. They would also be color-coded to show damage, and exchanges of fire/explosions would not be shown in detail, to encourage players to actually look out the window sometimes and behold the glory rather than live and breath inside this holo-map. I'm still a little undecided about whether this low-detail thing is a good idea. If anyone has any input, I would very much like to hear it.
The system-wide holomap would show fleet locations and rough compositions, in addition to planets, space stations, shipping lanes, etc.
The player would carry a handheld holographic projector at all times. This projector would have three main display regions, each of which could be expanded (by pushing out the others) for more detailed information.
The first would give information on the damage to your ship during battle, including a "schematic" view of your ship, listing a brief status for each of the critical systems. In expanded mode, you would be able to scroll through all of your ships systems, including all support craft and ground units, and view the status of repairs, set limited repair priorities, and generally micromanage stuff.
The second display would project a view of your selected friendly target or group, including general damage (shown as a color-code on the ships name) and current orders. In expanded mode, you would be able to view detailed damage reports for a single ship.
The third display would show a view of your selected enemy, neutral, or other non-friendly target. It would display shield and hull strength and known damaged systems (much of this information may be inaccurate due to the nature of war, but it should give you a good general idea). This last view would not be expandable because I can't think of anything else to put in it.
All together, I think these displays should take up roughly the bottom left 1/6th of your screen and should be visible at all times, unless you turn them off. A "3-d look" to them, along with some little hologram colored stuff below should be enough to remind you that they are indeed a hologram, not a permanent part of your vision.
The number keys would snap your view to an appropriate officer, and bring up one of the following menus, with the listed subchoices. Each of these commands that pertains to a ship other than yours will be issued to the selected friendly or battle group, or to all ships if none are selected.
Fleet Command (com. officer) - attack selected target, defend selected target, ignore selected target, disable selected target, board and capture selected target, cease fire, proceed with goals, recall all fighters (from that ship), reform around flagship, retreat (random micro-jump), go to nav. point, preset formations menu, go to fleet strategy room (would leave second in command in charge of the bridge). Choosing the strategy room would load a seperate room with giant high-detail holoprojectors, many different scale maps, 2-d extruded maps, homeworld style fleet controls, and oodles of stuff you can do. Note that this would not allow you as much control over your own ship, instead trading it for control over the others. This would be a good area to be in if your ship is on the outskirts of a system, not fighting itself, and you are commanding an assualt on the other edge of the planet; or if you need to redefine some goals or nav points real fast. However, this is a bad place to be if your ship is in heated engagements, because you wouldn't have the same options for your own ship as you would for other ships. This is purely to balance this aspect of the game and keep it from turning basically into Homeworld.
Fighter Command (Bay officer) - attack selected target, defend selected target, ignore selected target, cease fire, proceed with goals, reform around mothership (ship launched from), dock with mothership, launch all (applies to your ship only), go to nav. point, go to support ship management room. The support ship management room would not include battle maps and stuff. That sort of control can be handled from the fleet strategy room. The support ship management room would allow you to set custom mixed squadrons, including transports, landing craft, and shuttles, recall individual ships (as opposed to an entire squadron), set wing leaders, and stuff like that.
Ground Assualt (Imperial Army Commander) - launch pre-planned assualt (this would have been planned in the battle planning phase I talked about on the last page, before the battle starts), recall assualt (all ships), go to ground assualt strategy room. The ground assault strategy room would list all the availible ground units and resources from all ships at your disposal. It would have a large 3-d holo of the planet, with key cities and resources marked and color-coded according to allegience. Other projectors would have detailed 3-d maps of battlefields and key areas, allowing you to plan assualts, along with insertion and extraction points, set goals, choose commanding officers and what units to use, or modify goals, etc. in real-time battles in-progress. You would even be able to micromanage assualts, or have several going at once (with several good army officers commanding them). In this way, I think the true scale of a planetary invasion would be preserved, without making it impossible. Pacifying a planet should not be an easy thing, but capturing a bunch of key cities and natural resources should simulate it pretty well. Keep in mind also, that your ship can leave troops on the ground to fight for a couple of cities while you go and do other things, only to come back later to pick up your troops after a permanent team has arrived. Of course, this would mean that your troops would have nowhere to run if things got hairy, but that's the price you pay.
Gunnery (gunnery officer) - attack selected target, defend selected target, ignore selected target, disable selected target, board and capture selected target (yeah, I know, it's not gunnery, but where else to put it), fire at will, prefer support ships, prefer capital ships, cease fire, go to orbital bombardment room. The preferences as to support vs capital just means that given a choice your gunners will choose one over the other. The orbital bombardment room would basically allow you to choose a key location on the planet that is within your ships range (city, or whatever) and blast the shit out of them from orbit. This is a good tactic to soften up enemy defenses in preparation for an invasion, or to open up a landing zone for your troops. You could choose saturation fire (turn everything into smoking rubble), military targets (fires on troops, guns, defenses, and military installations), civilian targets (fires on power plants, waterways, bridges, highways, etc.), or free targetting (allows you to set specific targets to be destroyed from an orbital scan). Of course this would all be useless if they have a planetary shield, unless you happen to have a torpedo sphere!
Hyperspace Navigation (Hyperspace nav. officer) - emergency retreat (random micro-jump), jump to hyperspace nav. point (preset in planning phase), hyperspace jump room. The jump room would basically let you jump wherever you wanted in real time. There would be a certain ammount of time neccessary for your ship to calculate the jump path (with a blind micro-jump, it would be negligible), and your ship would immediately disengage any targets it was firing at and orient itself for the jump. This would allow you to jump back and forth between two battles or two planets in the same system, to drop off fighters or troops, or update orders to a battle line, then jump back to fend off some rebel attack elsewhere. The scale of the jumps, I think is very important. You should be able to jump from any one body (planet, moon, etc.) to any other, or just to some point in space. However, intersystem or intersector jumps would take too long and any battle you left would be over by the time you got back. Garrison moons and the like would actually be important, since they are close enough to the planet to reinforce it quickly, and so an assault on that planet would like have to take out the moon first, or launch a simultaneous attack. Multi-front attacks would also be feasible. You should also be able to time your arrival at a place (more on this later under pre-planning).
Sub-light Navigation (nav. officer) - pitch (generic 90d. port, etc.), yaw (same), roll (same), go to nav. point, go to selected target, hold, manual control (requires walking over the nav. station), go to set orbit screen. This last command would pull up a model of whatever body you are near on your personal holo-projector. It would temporarily get rid all other images from the projector and almost fill your screen. Here you could set the path of your ship's orbit, its velocity, and its altitude.
Before each mission, you and your officers would meet in the fleet strategy room and set up a plan of attack. The options here should be very diverse. You should be able to assign ships to different battle groups, assign officers to command each ship, redistribute ground units, set formations, set nav. points (which are very important, unless you want to manually pilot your ship all the time), set hyperspace nav. points (regroup point, etc.), set goals for each battle group, adjust the timing of things (ex. when the second arm of a pincer jumps in) and set triggers (ex. when reinforcements arrive, move to this nav. point).
Anyway, that's my vision. If anyone has suggestions, or if I left something out, feel free to say so.