I don't think she is a Dominatrix, I think she is just a waitress who doesn't mind indulging her partner's fetish. She said that Pullman left her a month ago to try to get his wife back and that she was seeing lots of other guys since he left (probably not true). The black stuff under his fingernails are bruises which Pullman keeps self re-injuring because it reminds him of her.
Yes there were a lot of nice ass shots and sexually suggestive shots that are not normally shown on TV. I wonder if the beach scene was so sexually suggestive to make you wonder what you would have done in a similar situation. Gratuitous sexuality with annoyingly loud music, in a public place with your family with lots of children around, is that enough to make you snap or at least say something. I know I was a little disgusted with their behavior and felt they should have chosen a place with more privacy. It would be funny if some 13 year old boy was filming the couple making out and the jury thought the couple were being indecent on the beach and Jessica Biel had every right to try to convince them to stop what they were doing.
Jessica Biel is famous for having a great ass, and yet they went out of their way not to show it as they followed her down the beach to the water. They showed more of her ass than I thought they would during the shower scene, but they still didn't really show it.