Very sorry for not responding back to this sooner. Yes, you're correct that we don't currently have any plugins for importing Facebook data into CiviCRM. Of course JFBConnect does create 100% standard Joomla users, so anyone that registers with JFBConnect / Facebook will be able to be used by CiviCRM or any other Joomla extension without issue. Obviously though, importing profile data can be very helpful too.
I've honestly never used CiviCRM, so I don't know about the hooks it provides. While we keep intending to create a profile plugin for the User - Profile plugin that comes with Joomla, we've simply never had any requests for it. It actually surprises us a bit as well, but most people that want profiles seem to opt for more powerful solutions like JomSocial, Kunena, or Community Builder which also support avatars and more flexibility.
As for creating your own plugin, we'd definitely recommend checking out our
JFBConnect Profile Plugin developer guide
. That guide was created for the 4.0 version and hasn't been updated enough recently, but it's pretty accurate and should give you a good overview. Looking at other profile plugins may help as well.
If you do plan to create a User - Profile integration plugin, we can gladly help out with any questions you have. We'd help with any questions either way, but obviously, we'd like to get that plugin out as well.. so that may help push us a bit if you're already going to be working on something.
Once created, if there are hooks in CiviCRM to pull in that data, great! That should do what you're looking for, but again, I haven't used CiviCRM, so I can't guarantee anything beyond what you've told me.
Hope that helps,
Alex