bleh, the human element The best way to combat that stuff in my opinion is with the human element, that is more along the lines of option B above. Things that are automated like disallowing free email accounts are spotty at best, you'll certainly be blocking legitimate users and who wants to try and maintain a list of free email accounts to check against?!
Premoderated even seems a bit drastic to me but you're the one doing the cleanup and disciplinary action, if it'd save you time on those kinds of duties then I guess it'd be mighty attractive. Then again, it would tend to annoy people and drive them away if they ever bothered signing up. I've personally not stuck to any community that did such things, or required rewards to post in certain more attractive areas etc, that annoys me.
I would suggest patience, IP logger, and IP/Email address banning facilitation (don't ban ranges!) and the human touch!
Trolls suck, but I've always managed to ignore them, same with spambots that sign up accounts and spam the boards, delete, ignore, then eventually the cycle turns and they quit coming around.