Your welcome,
As for joining the domain. I believe the answer is yes. I use VPN to connect to my machine at home, there I have Windows file sharing /
Samba running. File sharing is not accessible from the internet on my network, however once you enter on the VPN, the remote PC has an ip address inside the LAN therefore you can browse file shares.
Once you connect a client with VPN you will appear to be on the same network as the VPN server.
Hope this helps. Domain controllers and such are not my strong point.