Network Theme Search

Hey Guys!

I'm trying to make the blogs search work in this theme.
I've already set the sub-site creation of my WPMU network, now I want to let users create sub-sites from the BP main site and let they search this sites and contents.

How can I enable that?

Is there a way to enable to just a type of user? I mean, if I use the Buddypress User Account Types plugin to create two different user types: User who can't create sites, user who can create sites and the button "create site" appear just to the user who can create sites. Is it possible?

Thanks

Derek