Where is the options page?
Settings -> BP Group Control
Can I make it so only site admins can add people directly to groups?
Yes. All of the abilities provided in this plugin can be restricted to site admins, group admins or nobody. If you just want to use the identifying groups functionality, you can do that. Identifying groups also have the same permission controls.
Can I set permissions differently for public vs. private groups?
Yes.
What does “make identifying” mean on those buttons everywhere?
It means clicking will make the current group the identifying group for either yourself (if it is on a group homepage or your “my groups” list) or another user (if it is on another user’s “my groups” list). Can any one think of a better wording for this button?
How can users/I add people to their groups?
1) during the creation process, and 2) on the edit screen (admin->add/add existing).
Does BP Group Control send emails to new users?
Yes. You can choose to either make up a password for them and email it, or generate a random password (in which case it forces you to email it so that the account isn’t impossible to access).