It seems the server is quite dumb-ass and only blindly copy/paste positions and orientations. I mean just have a look how does the second player warp all over the place.Ok, it's early version, but I'd hessitate to call that usable.
Does it work if you have a Fallout 3 in steam?
As long as it's the right version and it's uncut, then yes.
I played that with a friend . It was good but the animation don't sink and the VATS is not yet disabled.