Facebook Connect is a way of connecting your Fanpop account with your Facebook account, so you can share content, picks, quizzes, comments, etc from Fanpop on your Facebook account.
From Fanpop:
"Share your Fanpop activity with your friends on Facebook!
If you connect your Fanpop account to Facebook, you'll be able to automatically share:
* Your picks
* Your quiz questions
* Your answers
* Your favorites
* Your new content
Don't worry about flooding your Facebook stream with Fanpop activity. We'll make sure you don't over post."
I don't think so, but I'm not 100% sure. Fanpop itself will gain access to your Facebook, but only for your own use. There's more information about Facebook Connect at this address: link