I dont really know about the framework, but I can answer your questions as far as number of players and FPS. The number of players depends on the version you buy. Standard and extra do not support multiplayer games. Commercial - 200$ - suports 1-4 players, and professional - 800$ - supports unlimited players. You can also buy populace, for 150$ i think, that works with any version.
The FPS largly depends on the type of game you have made. If you have shaders, particle effects, and hi-def modeling everywhere, you game will not run very fast unless you are running a high-end computer on a LAN or through cable/T1.
I dont know about the templates, I never use them...
About gamespace, I dont feel that it is worth it. However, this is my PERSONAL opinion. I tried gamespace light, and did not like it at all.
Sorry, those are the only ones i can answer, maybe someone else can pick up where I left off
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