Don't worry, I can think of . . . creative restrictions. And yes, hero factions and villain factions from all universes are available. As it so happens, it is precisely however long it was after the ending of the Fifth Season of Babylon 5, or the last season of TNG, etceterar. (By that I mean, if it was 2262 by the end of Crusade, it's 13 years later now.) Also, I"m not an expert or that knowledgable of Star Wars ten years after the Emperor bit it in the reactor of the Death Star, but it's say, uh, 29 years afterwards. (Seeing as it's 2012 now)
Also, as GM, I have the power to restrict everyone's use of powers. I will try not to be an evil genie and turn your powers against you, but I can, if I wish it, simply cause it to fizzle out.
Okay, for SW, if we count the EU, that puts us between NJO and the Dark Nest books. If we go from the end of Crusade, rather than from Sleeping in Light, which fast-forwarded 20 years, so SHeriden is still alive and probably still president of the IA. Maybe we can even save Londo, if we organize and act quickly. Having the Centauri Emperor owe us one would be nice for purposes of legitimacy, even if a Centauri battlefleet is unable to add much against some of the threats we'll face.
We can probably establish a pretty good rapport with the SGC, both being small groups with technology considerably above the norm. Then again, they, and everyone else, will probably be suspicious of our motives and off-balance from the sudden materialization of so many unknown empires. There is also at least a small problem in that even our allies are likely to covet our advanced technology.
Oh, btw Demiurgas, if this thread follows the same pattern as the dragon rar before it, expect several people to flood in once you get a decent post/page number and proclaim that with our advanced technology and powers we should really conquer the universe, for it's own good, of course. If you object, expect them to call you overly restrictive, if any of the rest of us object, they will say that we are setting up an opressive facist government that will be impossible to maintain in the long run, that they reject the authority of our emergency government, which is really just a bunch of internet nerds dropped in the situation and picked democratically.
They may also try to kill the rest of us, then say we have no moral authority to imprison them or in any way hinder their murder attempts.