I've got file sharing working. For those of you interested in this setup, what I did was start a WINS server on my DC computer in the 10.0.1.x network. Then on the outside firewall I added the WINS server IP, DNS server IP, domain name, and domain search list under services–>dhcp server-->LAN. After doing this I was able to resolve internal websites, and access network shares from a client computer on the 192.168.15.x network.
Now that the test setup is working, I'll try adding a few more client "sites" to the mix and see what happens if I expand the setup a bit.