You can use gs for Master Server, client+server , or p2p clients or just client.

But as i said you may consider using an external library while building your server. If you use GS while building the game(clients), you need to use either gs or a server developed using a7 sdk.

Your clients doesnt have to include the server. Same applies to server. It doesnt have to include client.

I dont know how many users current mp system can handle, and i cant know what a superb machine is(it cahnges from person to person, i also cant know, how the game and server programmed, how they use sources etc.

Giving a exact or close nuber is impossible.

Good Night,
Quadraxas.