[1]: That is, apart from the login and pulling in your list of friends so as to populate your "Friends' feed", we don't use Facebook IDs or names at all.
Why would you want to have an anonymous conversation on facebook anyway? Sorry, don't get it.
For "rogue" friends, we have on our roadmap a mechanism to "flag" users for a review of their postings. That'd trigger an admin banning them if necessary.
The facebook component, is intended to be for a couple of things. Firstly, to allow you to restrict your discussion to just your friends (there are several scenarios in which you'd like their opinions, but you suspect they might not be completely honest with you if you knew who they were). Second, it allows us to be able to keep out bots en masse. The assumption being, of course, that Facebook polices its user-base to keep them out. In turn, the general quality of the discussions stays decent (well, for an anonymous platform, at least).