Have you searched the thumb drive for the map file?
The complaint about the GameAPI version is about the game DLL. I suspect you installed from a Quake2 3.05 original CD and that was a version that didn't support multiplayer. You need to download and install the Quake2 3.19 and 3.21 releases. This will update the game DLL to version 3 API.
Oh, there is a leak SOMEWHERE. I've found them before by building a box just outside and around the whole map and then looking for parts of it lit up.heh, Quark has a handy ckeck map feature that is good at showing you where the leak is. Used that before as well.