INVITE registration ON BUDDYPRESS

Hello,
1) I would like to create an invite only buddypress site. Ie people are visiting the site and they fill a form to receive an invitation, a mail to acknowledge their acceptance to the site.
So not an automatic mail sent but a reveiw from admin.
2) in the form for invite, I would like guest to fill a couple of xprofile fields, what is the best way to do it, to put the fields in x profile. do you have a good looking registration page plugin in mind ?
Best regards,
Hervé