Well, I can only answer some of these questions... mainly about the frontend...
Most frontends allow use of only joysticks and buttons (remember, most interfaces treat the joysticks and buttons as keyboard strokes!) From what I have discussed previously, no frontends, that I can think of, allow for online gameplay such as Xai Link (or whatever its called!), etc. Well, not intergrated seamlessly anyway.
You can get your computer to boot straight into any frontend with a bit of regedit knowledge or simply by using 'instantsheller' (very easy to use and very good!)
As for PC spec - well, I'm no expert but from experience you would probably want a 1ghz processor at minimum and 512MB RAM minimum if what you're mainly into is 2D - 3D requires A LOT more.