SEP 11.0.6 and above are supported on Windows 2008 R2 , Windows Server 2008 Hyper-V
Make sure you have 4 or GB or RAM

Performance will depend on what other application you will be running on the server however if you are haing more than 4 GB ram then it should be fine.

System requirements for Symantec Endpoint Protection and Symantec Network Access Control 11.0.
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2010041307181848

is it ok to isntall SEPM on a domain controller?

Yes, Its absolutely fine..

Yes, I am using it on 2008 R2 64 bit

Yes,, it is....
 
About Symantec Endpoint Protection support for Microsoft Windows 7 and Microsoft Windows Server 2008 R2
http://service1.symantec.com/support/ent-security.nsf/854fa02b4f5013678825731a007d06af/b09d685c029bec68882575ec0076f089?OpenDocument

Yes, it  is ok, to install ru6mp1 on a Hyper V, and you  could install on a D.C too!!!

I've always run SEM or SEPM on VMWare servers and earlier this year put the latest SEP/SEPM on Server 2008 R2 (64bit) and have had no issues that are a result of the VMWare.
It's smooth. I will say it takes some HP so configure accordingly or you'll find SEM wants more processor or memory than it's got.
I give it a large base configuration (4 gig RAM, 2 dual core processors), but it can "rob" from others when needed.
I know of others using it just fine on other virtual products with no issues.

I'm really glad you folks typing in ru6mp1 aren't missing the 6 in there...............