SysPrep on a DC

The short story is don't - one of the effects of SysPrep is to change the server's name and that causes domain services to fail in such a way as to make the machine not boot-able.

It's possible however, that one could;
* configure the .xml to not allow a host rename
* add a post configuration step to do a netdom based rename
But I haven't high hopes

There is a way to enable auto logins at least. From an elevated command prompt:

reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v AutoAdminLogon /t REG_SZ /d "1" /f

control userpasswords2

Check and then Un-Check the 'Users must enter a password..." and supply DOMAIN\Username in the pop up