love
The answer depends on whether you are measuring the age of Facebook from when it originally launched as "Thefacebook," or from when it was opened to the public. Facebook was launched in February 2004 with membership restricted to students of Harvard College. It wasn't until September 26, 2006 that Facebook was available to anyone age 13 and older with a valid email address. Twitter launched publicly on July 15, 2006, making it older than Facebook for most users.
Just join using your Facebook account. If you are not on Facebook, then first join it.
you don't
You can't.
You cheat and say you are older than you really are.
you just link to facebook its that easy.
you can't
A lot. Using facebook is not really restricted to any specific religious groupings.
Restricted Groups
You can do surveys for free Facebook Credits for membership. for free treats
On facebook, when you restrict a friend you are limiting what they see. They can only see things that you post that the public can see.