They want to see prints, unmounted. As for framing, some galleries do it but they make you pay a lot more than its worth (squeezing artists on framing is often their main source of profit), so basically you are always responsible for framing. Yes commissions are around 50%, though some are less and a few are more. Expect that most of them will have absolutely no desire to talk to you and will act as if you, the artist, are little better than a cockroach running across their floor. That attitude is counter productive but very common. It usually takes knowing an artist already represented, or knowing a staffer to get them to talk to you, though in smaller cities thats not the case.