Question 1: What prior versions of Windows Server can be upgraded to Windows Server 2012 R2?
Answer: We have a great article here that talks about what can be upgraded and what prior versions should be migrated.
Question 2: If I install the evaluation version of Windows Server 2012 R2 to test it out, can I convert my evaluation version to a retail version or do I have to reinstall Windows Server 2012?
Answer: You can convert your evaluation version to a retail install. Check out the same article in the section Converting a current evaluation version to a current retail version for details on how to convert.
Until next time,