It is totally possible to do that. But the editor for the source files does work though. Because I'm not sure if this issue will ever be fixed.
Yes, everything works correctly with the source files.
If my level uses new models and textures, then the source files directory should be similar to the game directory?
You don't need to fiddle with source files, if all you're doing is making levels. That's for the internal structure of the game.
