Move RRAS from SBS 2003 to Windows 2008 R2

Hi Experts,

I am separating the major functions of an SBS 2003 server into a Win 2008 R2 server and an Exchange 2010 server.  I am looking for guidelines/best practices for moving RRAS used for VPN access.

I've created a new domain controller as a start.  Everything is sitting behind a Cisco 5510 router/firewall, with rules pointing to the old server.

Here are my questions:
Is it OK to move the VPN to the new DC or is that not recommended?  Should it be on another server instead?
Is there a simple way of moving the settings to a new server?  I saw some powershell stuff but it seemed easier to do it manually (according to youtube...lol)
How can I test the new settings without changing the firewall rules to port forward to the new server?  I want to make sure everything is working properly and not impact the users?  Can I change the PPTP port on the new server and forward the PPTP request to the new server?  If so, how do I change the setting on the client port?
How would you suggest migrating the remote user settings to use the new server?  I can't use a DNS alias because Exchange traffic comes over the same host.

Thanks for the assistance.

S.....