Reinstall Active Directory

I have a single Windows 2003 Server with Active Directory.  Unfortunately, I have a single lable domain name.  I now have DNS issues.  I have read why and mostly a Single level domain name is the cause.  What I wan't to do tonight is
Uninstall AD with DCpromo.  Then Reinstall a new Active Directory the right way.  mydomain.local.  I have some parts to this question

Part one: Do I have to do anything with my DNS prior to uninstalling my Active Directory or will the uninistall take care of it?

Part two: Is there anyway to save my existing 35 computer and 35 users that I have in my single lable domain now? If so how?

part three: My users are in the domain AATCINC.  When I change to AATCINC.local will I have to do anything with each of the 35 PC's?

Part 4:  I only have one GPO policy that inhibits users from accessing the control panel and not able to install.  Will I have to do anything with Group Policy before I uninstall?  

Your help is much appreciated.  If I had more points I would give them.  Real headache not setting up the AD like it was supposed too.  

Net