[Samba] Samba 3.0.24 - group permissions

[Ralf K. Wiegand]

Hello - I upgraded from FC4 to FC6.  My samba configuration (samba
3.0.1x) was working just fine until I upgraded to FC6 and Samba 3.0.24. 
I had shares who where protected and only some users and groups can
access them.  I used valid users = @wireless, where the group wireless
had 10 users.  Before the upgrade this was working just fine.  Now
nobody from @wireless group members can access the share.  For the
moment I got around it by listing every user of the group @wireless in
the "valid users = user1 user2" line.  I did some research and found
that samba version 3.0.24 uses something called "getgroupmap".  OK here
are the questions:

q1) How to include my existing groups into the new samba setup, without
redoing everything.
q2) My server is a PDC, is it possible for samba to act as a AD controller?
q3) What is the correct way to setup a PDC using samba 3.0.24, and have
the group permissions work correctly?
q4) Are there any how to's on working with the new group permissions and
why did it change?
q5) Some of the research was mentioning off group permission problems
and bugs within the new version of samba 3.0.23 and greater.  Is this
also the case with version 3.0.24 and how do I get around it?

Thank You
Sincerely,
Ralf Wiegand