I can respond to question 1 (I'm at work...)

Nudity is "not done" in Ambergris Caye - on the outer atolls - yes (or maybe if you can find a private spot north of the cut on AC), but otherwise, definitely frowned upon. There was a completely flat-chested, but gorgeous Italian woman who did go topless the week we were at Banana Beach - and most American guests (except for me) were pretty freaked out. She did ask the staff at Banana Beach if it was OK before going topless.

Otherwise, I would say AC seemingly caters to a conservative hard-drinking crowd, and you can find whatever you are looking for - but don't expect NYC quality!