Rosario Dawson perfectly shaved smooth body with no visible tan lines shows that she probably is a nudist in private and feels most comfortable bare naked with no single hair hiding her exposed skin.
Probably because she most likely wore a merkin during the scene. There's a ton of articles about her talking about there being an entire room just for merkins. I know she was shaved, but maybe there's hairless merkins too. That's explain why you don't see her lips.