How EXACTLY does Jconnector work?

[grindhouse]

I really REALLY am finding this a big problem to understand!

Please tell me if I am right or wrong in my understanding:

Someone comes to my site for very first time, they see a 'connect with facebook' icon and hit it.. they are not registered as a new user (or are they?) if they are a returning registered user and hit connect they sync that account with the facebook one?

if they do register as new user, is it by email address? no because facebook doesnt give you that..

what if a registered user is not logged in and hits connect? will a 2nd user for same person be made? then what?

I'm finding this head-work.. I was thinking about only allowing registered users see the connect button but that would defeat the point of easy login LOL! they cant see it TO LOGIN!

HELP ME PLEASE!

Also if I have someone sign in with open id they are bypassing the registration and now on site as registered users but not on database.. does it work same way?