Hi Tpullins,
1. If uses will be connecting from outside your company's network, you must deploy an AD FS 2.0 proxy. You can find the detailed information in this article: Prepare for single sign-on
And if you have a DMZ running web services you could add the ADFS Proxy service to that, however as far as I know we do not have any articles about using proxy servers in the DMZ instead of an AD FS 2.0 proxy. Here is a related thread: http://social.msdn.microsoft.com/Forums/vstudio/en-US/839f2a32-b95b-4d5a-9418-e5d06efab32f/configuring-and-adfs-20-proxy-on-a-dmz-server
2. We recommend you install the internal AD FS server as a federation server farm.
Thanks,
Bourne Zhang