Hmm.. That's definitely strange about the username. What is the setting you are using, just hide? What is the auto-username creation value set for as well? Also, in the JLinked Administrator page, can you verify that all the versions are up-to-date and correct?
As for the Facebook button showing when it shouldn't, is that on the Login / Register page that a user goes to after clicking the Login with LinkedIN button? If so, that's the correct behavior. We don't actually have an option to hide that button on that page. If JFBConnect is installed, we show the button. Did you possibly create a template override for that page which could be causing some issues? If so, it may also be the cause of the username problem above too. If you have a template override, I'd recommend trying to rename that file, temporarily, to see if things work right. If that fixes it, you'll need to integrate the changes from our latest release into your override.
Hope that helps, but if not, just let us know and we can investigate further.
Thanks,
Alex