Well the way you have it now will definitely force users to register... But I wouldn't suggest you keep it like that. I have no idea what I am registering for, and can't see ANY posts. Try to edit this so you can only see a couple forums, but have to register to see the rest, and be able to post.
I would do that. But i read somewhere bots can't index those places. I have a VIP section though just fixing it up.
Blocking guests from reading your content is a turn off to many guests. When I google for something and fall intyo a forum with blocked content, I'll head back to the next site in the SERP rather then register. A member only forum is fine, even a few are fine, but they should not (and never be) the norm, unless it's a private forum.