Sadly, Google doesn't allow adult material in adwords, adsense. The terms must be "clean" and have SFW landing pages. The closest to adult you will get on adwords or adsense is the dating sites where people link to Hotmatch, POF etc, with risque terms. Companies such as Adbrite used to allow adult and probably still do.
In terms of sending PPC targetted traffic like that, Most programs will allow and encourage that, but linking straight to the signup page may not get you the right conversions your looking for. You'd be better off buying the adwords and targetting them to tours or specific girls or specific niches... like buying 'lesbian membership' and getting it to a good tour page or very good standalone promotion page. Say if was a search term like
Taryn Thomas and you linked directly to her
cam page it would be better than linking to a signup page for a bangbros site she might appear on.... but again it's probably easiest to warn you that Google Adwords targetted PPC is a LOT different to other traffic sources (particularly adult PPC).
If you're doing dating and cams you could set up clean landing pages and put the PPC traffic through there with google, but they can be touchy and soon as they sense adult. In terms of your questions around targetting directly for site names, I can't see a lot of sponsors having issue with it... although sites like Bangbros, Brazzers, Homegrown Video and Playboy will have trademarks on their names and if you SEO or Advertise for their direct names, it will be within their TOCs to can your account under their trademark protection policies.
Hope this has helped!