If you already have a Gamer Launch account connect your Facebook account on your user profile first before using Facebook connect to login. Otherwise you may end up with a new account.
I saw the trailer and caught the bug, so figured I bought the expansions on both my accounts. I doubt I will have time for full time raiding, but I'll be around for the occasional instance.
You'll be in good company. There's a Facebook comment/thread that called out about 8 of us I think? See you there.