BuddyPress: Approve Users and Create a Private, Closed Community


I have BuddyPress in my WPMU theme - and want it to be a closed community.

I need to approve users before they can login - and I want to be able to restrict non-users from viewing information about my other members, their groups, and their activities.

I need my BuddyPress community to be truly private.

Please tell me how to do this.

Thanks in advance!