[For 1.6] [Updated] Invitation System

[ForoGCF]

Hey:

I've just installed the plugin but I have a few questions:

Can I set it so registered users can send X number of invitations? Can only Admin send them? I don't want normal users to edit invitations, only send them.

Yes, you can limit the maximum number of invitations an authorized usergroup can send using the "Who can use Invitation Management" setting in your Admin CP.
Normal users can view and edit only the invitations they sent.

I've seen Users can modify the limit that they can use a code. Can I fix it to a value that they can't change? And How I can add a custom group in a "Who can use Invitation Management"? (Sorry about basics questions)