#2
Depends on the crowd, if its a rockish crowd, they probs won't like rap but who knows

Personally I loathe the stuff
#3
i'd say not for your first gig. You can experiment once you've done at least a few but stick with something solid and try to get some sort of a name wherever you play before you try something like that. I can see that blowing up in your face much more likely then everyone loving it.
#4
I think it's a good idea. This way you get to do the cover your own way instead of just copying what's already been done. Just make sure you do it well.
WARNING:This post contains explicit portrayals of violence; sex; violent sex; sexual violence; clowns and violent scenes of violent excess, which are definitely not suitable for all audiences.