Getting Closed Beta Site w / FB only Login to work with launchrock launding page

Working on implementing a new landing page for my site www.goodtogoout.com. We're going to make some changes to the staging site gtgo-staging.heroku.com, which we then push to production, but I'm going to go to FB for login only and do a closed beta while still collecting emails from stakeholders via Launchrock. I'm wondering if anyone can offer any advice or help keep the site private while using Open Graph for login / registration. Want to be able to pass on some overarching advice to my developer, or hear something that might discourage me from this idea.

Thanks in advance for your help.