If the first question is what did I sign, the answer is; pay the bearer of this form one million quid on demand!!!!.
Without being all doom and gloom, one of the early rules to learn as a pro, is to be very aware about what you sign.
It could be that you have agreed to terms & conditions imposed by the venue on how and where you can use your images and even for what purpose.
It may also have been a whole heap of health and safety type rules and regulations for you to comply with, while you were at the venue.
Maybe they were asking you to confirm that your public liability insurance, did cover certain aspects of your being there.
Who knows, just be aware for the future, this job can be hard enough at times, without extra issues popping up.
Aye your right enough, the three song rule is usually three songs and your out of there. It would seem the stars don't want hot sweaty shots of themselves working, I can't see why not.
Flash is not usually allowed at all, but these "rules" do vary from venue to venue.
So how did it go, did you get some stunning images from this gig?