It will be possible to host many forums within Free Republic. Each forum would have its own management features, user list (with independent user levels), moderators, etc. Some forums may be private, some may be created for special projects, some may just be alternatives to Free Republic.
Whew.... massive, yes. I see that you are pressed for time, but when you get time, I would be interested to know why these changes are being made, why would you want to "decouple" articles and comments, and what's this about "private" forums? Could end up getting a little "cliqueish" around here, no?
Anyways, good luck with the move.
Private forums. For example, planning committees for Free Republic events may wish to have their own private forum. And there already is a "Forum Advisory Board" forum and Moderator forum, both private.