Let your BuddyPress users block other members from contacting them or viewing their profile.
No. Members can not block anyone who has the "edit_users" capability.
define( 'BPB_ADMIN_CAP', 'capability' ); to your themes functions.php file.
Yes. Visit your profiles "Settings" page where you should see the "Blocked Members" page link. Once on this page, you can select to unblock anyone in your list.
Yes. Add your own templates for both the blocked and blocking files in the