There have been a few times in my campaign where the PCs have wanted to know something about the Imps, either regulations or standard procedures or something. Where a check was called for, I've tended to handle this under Knowledge(Core Worlds), but I was wondering if any of you have a different take on it. How have you guys handled this?

Knowledge War.

A new skill or one of the existing according to the topic. General info about COMPNOR, I'd say Core Worlds, but info about COMPNOR activities in the Outer Rim that falls under different skill. Boost/setback according to characters background.

If you are wanting information on just generally what the Empire does in the day to day routine, I'd suggest either Core Worlds or Education. Depending on the circumstances, I might even see Streetwise being used with an upgraded difficulty or setback.

It's tempting to go with Warfare, but that is specifically for tactics/history related to military engagements and wouldn't really apply to "How to renew my Space Driver's License"

Education is what I would use. Education can be pretty broad, but generally I believe it can be used for nearly anything you could get a basic college degree from. In this case, I would relate it to Government or Law.