We expect to have a large number of forums.
Is there a way to assign the rights to a User?

Yes this would be very helpful.

Can't you just create a Role in DNN, assign some users to that role and then in the AF Security / Permissions area assign whatever permissions you want the users in that role to do?

Not sure what the exact question is, but here is a guide regarding moderation: http://www.activemodules.com/active...rol-panel/