BuddyPress.org

1. WordPress (without BP) only has three required fields for members – username, email and password. On the BuddyPress registration form these are required fields. it also requires a name and any other required fields you choose to add to the base group.

2. The best place to find documentation is within the code. Not exactly what you wanted to hear, but theirs not really anything as in-depth as you can find within the comments scattered throughout it.