Where is the Empire getting all of these Inquisitors?

[Galvatron]

I don't recall anything from either the novelization or the new EU Tarkin novel that indicated he knew the Emperor's plans for the Senate.

As for Vader and the Emperor, I can't remember if it was in the old EU or the new, but I do remember a passing line by the Emperor in which he indicated disappointment with Vader's loss on Mustafar. It wouldn't surprise me if the Emperor reminded him of it at every opportunity to keep Vader in a constant state of seething rage.

[Q99]

Disbanding the senate is something that takes preparation, making sure they're accounted for and don't cause trouble.

My assumption would be that they knew it was in the works, but not when it'd actually happen. Or at the least, those individuals can guess simply because they *know* Sidious, and also know the 'Tarkin Doctrine' that he'd been pushing.

Galvatron- I know the new Vader comic has a line on that, but it might've also been elsewhere.

[Galvatron]

And yet even a high ranking general thought it was "impossible" after Tarkin announced it. My feeling is that even some of the most hard core militarists couldn't imagine the Empire remaining functional without the millennia-old bureaucratic infrastructure of the Old Republic and the Senate to hold it all together.

And their "preparations" sounded like little more than declaring martial law with the regional governors in charge and the threat of the Death Star to back them up. The Imperial starfleet apparently wasn't sufficient to bully the entire galaxy into submission by itself.