Chris,
Let's see how we can help, and thanks for the detailed explanation. Hopefully, I'll have some decent answers, but there are some limitations you'll have to work with.
First, I'm glad you're enjoying JFBConnect over JomSocial's implementation. Their on-site social network experience is excellent, but Facebook functionality is really an add-on for them... whereas all we focus on is the Facebook stuff. It's good to have focus
Regarding status updates, JFBConnect has it's own "Post To Wall" plugin. It doesn't let you set which user's status are pushed to Facebook, but it does respect the privacy setting.. only updates that are fully public will be pushed to Facebook. I honestly don't know how JomSocial's status updates to Facebook work, but that may be better (or, frankly, worse)
Now, the sticky mess of dis-associating account cleanly.. JFBConnect doesn't have a front-end way to 'break' the Usermap between a Joomla user and their Facebook account. Currently, only the admin can delete a usermapping. This has really never been something asked for, and I don't think you are either.. you just want users to be able to get in with their Joomla accounts (correct me if I'm wrong).
So, to get user's a password (if they don't already have one), we'd simply recommend putting up a redirect or notice on your site. The notice would be to let users know they can login directly, without their Facebook credentials if they just add a password to their account. This can be a simple menu item, front page article or module, or something else that has a link to their profile.
If you want to be more aggressive about making sure user's update their password, you can use something like our "Force Password Change" plugin (free). Currently, it's meant to force a user to update their password on their first login (good when you create accounts for users). It can be easily modified to redirect users (when they login) to their profile *if* their account currently doesn't have a password.
There are other options you could use that would specifically target any users that login through Facebook, for instance, but I honestly think either the passive notification (Did you know?) or the aggressive one with a forceful redirect will let the users that care, know. Of course, emails or newsletters mentioning the ability don't hurt either.
Hope that explains some options. Certainly, if you have a preference or other ideas, feel free to let us know and we can help you implement stuff.
Thanks,
Alex