Answering as best I can:
1) Short answer: no. Long answer: You can't send him to the wayfort if you haven't beaten the Alarune yet but you aren't locked out of doing it permanently if you do centaur quest before getting her to stop blocking the way.
2) His content is basically the same regardless of corruption, a couple talk options and some repeatable sex scenes. Only thing that really changes it is if you killed/spared the Alarune and that's just an additional talk option and small flavour text changes on his wayfort tile.
3) Don't have a definitive yes/no answer here but seems unlikely at this point in time.
