Re: B
In the short term, removing obvious distinguishing marks from chatmail servers seems workable. In the long term, giving all common e-mail servers optional chatmail capabilities seem preferable.
This seems to be happening already with Mox. There has been discussion of YUnohost and Freedombox on the forums.
I agree that being able to enable moderated Chatmail, with accounts limited to pre- or post- approval (using tokens etc.), would make stealth servers easier. It would make them use more human time, tho.