I have no experience setting up a live site, but I know the software is expensive! But you need good quality software to run a live site without having to deal with crap issues every time someone with a different os or browser tries to buy a show!

For billing, CCBill is a great option as is Epoch. I would contact both of these companies to see what their solutions are for live sites. Both are very helpful and have a lot of experience in the adult industry so should be able to assist.

Tips, presents, etc are all GREAT ideas. I have also seen setups where the show is free for a group, but they will only start "performing" once they receive so much in tips. From what I hear, those billing options do well.

Good luck with your new venture and keep us all updated with its progress.