How do I setup Active Directory and Group Policy on Windows Server 2012?

I work for a school district that uses a Windows 2012 server with about 400 Windows 7 PCs and 150 Mac PCs. We are set up with Roaming Profiles on the PCs and would like to be able to setup Active Directory, Group Policy, and Roaming Profiles on our macs. (We also have a mac server that they are using as a file server only) As we are a school, our funds are very low. Now for the questions...

Is there a software that allow us to accomplish this?

Is there a free solution or a very reduced price option to do this?

I heard that http://www.centrify.com/products/mac-edition.asp may accomplish this and I read something about it on here but didn't know if this is what I was really trying to do becuase it was marked as "The Golden Triangle" and did not mention Raoming Profiles. This is the link though: https://discussions.apple.com/thread/3280427?answerId=17200059022#17200059022

Any help would be greatly appreciated.