Eduardo,
We can help you with the email questions above if you'd still like. Just let us know.
To disable the Login/Registration functionality of JFBConnect, simply disable the SCLogin module and JFBConnect - User and JFBConnect - Authentication plugins. Leave the JFBCSystem plugin enabled.
Then, we'd also recommend disabling the "Automatically login Facebook Users" and the "Integrate into Joomla Registration" setting in the Configuration area.
That will effectively disable any logins with Facebook on your site.
Hope that helps, but if you need anything else, just let us know!
Alex