Considerations for AD & Exchange upgrade while ADRMS 2008 R2 is in place

Dear Fellows,

I am going to deploy highly available ADRMS infrastructure in an environment with Active Directory 2008 R2 and Exchange 2007.
I want some thoughts and suggestions (with references if possible :) ) on below:

1. Will there be any impact on ADRMS infrastructure if Active Directory is upgraded afterwards to Windows Server 2012.

2. Will there by any impact on ADRMS infrastructure if Exchange is upgraded afterwards to Exchange Server 2013.

3. Is it better to deploy Windows Server 2012 based ADRMS instead of Windows Server 2008 R2 based ADRMS righ now? is it supported with AD 2008 R2?

Any suggestions will be highly appreciated.

Thanks.

J.A