Hi there Ricster
WinGate VPN (either full WinGate install, or VPN only Gui version) is required to host or join a VPN.
Remote LANs wishing to join a hosted VPN need to have one machine running either WinGate(full) or WinGate VPN (VPN only without the full range of Proxy server features) to create a VPN. So basically as Adrien said, you need WinGate VPN installed and running on a PC at either end of the connection.
Machines on the networks behind these WinGate VPN PC's will be able to see each other in the Virtual Private Network if the WinGateVPN Licencing will allow it.
These machines do not need to have any WinGate software installed.
However I would suggest that you read our white papers on WinGate VPN
and routing so you have a clearer idea of the setup.
http://www.qbik.com/resources.php
WinGate VPN available under the downloads section is a VPN only WinGate (without all the other bells and whistles, proxy services etc as the full version WinGate ) for users who simply want to use WinGate VPN.
>>"Can multiple clients connect through the same port, which is mapped from the router directly to the wingate machine?"
>>"Is any port mapping needed by the client who is behind a router?"
As far as WinGate VPN operating behind a NAT translated firewall router,
Ports 809 udp/tcp (by default) should be mapped to the internal IP of the WinGate VPN machine so that VPN traffic from across the Internet will be sent to this machine once it reaches the routers firewall. You will need to consult your router documentation to see how to make changes in your routers firewall to do this.
WinGateVPN (again dependent on licencing) if hosting a VPN, can handle numerous similtaneous connections from remote VPN clients.
>>"Where do I find which LAN IP is being used by the tunnel. Does it request one from the routers DHCP, besides the hard-coded IP being used by the machine on which it is installed?"
Under the "published routes" in WinGate VPN will show all IP addresses that the machine is publishing across the VPN.
>> "When communicating with a remote machine which is also behind a router, do I refer to it by it's own LAN IP, or by the tunnel's IP."
If routing is correctly configured then you should be able to reach the remote client by the external IP of the router, (as the communication will be passed on to the WinGate VPN machine as I described above)
Hope this helps
Erwin