DFS ABE on Existing File Server

I have a couple questions about DFS.

We currently have a file server that we need to setup Access Based Enumeration on to hide folders the user does not have access to. The server is 2008 R2 in a Windows 2003 Forest & Domain.

I've read contradicting articles saying it will work on 2003 forest/domain level and another stating that it can work on a 2003 forest as long as the domain level is 2008.

My other concern is that i am taking an existing file server and adding DFS to it. I have backups in place but will adding a DFS Namespace and eventually ABE affect my current shares or permissions?