A. No, the PDC/BDC registry is different from that of a stand alone server, again a reinstallation would be needed.

As an alternative, you can use a 3rd party utility called U-Promote, http://u-tools.com/UTools/UPromote.asp however this works by making registry changes that would render your system unsupportable by Microsoft and may lead to problems later in the servers life time, for example moving to Windows 2000.

In Windows 2000 you can change a domain controller to a normal server by running DCPROMO.EXE.