We work extensively via VPN. Everybody needs to connect on their own, which is very tedious.
I am thinking that there needs to be a router (box or linux) that I can connect to VPN from, and then everybody joins its wi-fi, is able to connect to our servers made available by VPN.
Have you done this before ?
We are doing this at the moment, we have a router to router VPN tunnel that's open permanently. Anyone on the local network can see/interact with servers at the other end.
This Microsoft document may help: http://technet.microsoft.com/en-us/library/cc728081(WS.10).aspx
FYI: We are using Draytek Vigor routers.
If you can't install a router at the other end then perhaps another option would be to configure the VPN on one workstation and then share it for everyone to connect through it. At least then you would only need to configure it once.