they can be run on a clutch so they may be connected, but not operating.
a rebuild doesn't have to be done, it depends on how much boost/power is being pumped through it.
either way, unless you are hell bent on a supercharger, its a stupid waste of money, plenty of turbo kits available, will make the same power for a faction of the cost.
putting on a SC whilst still on your p's is another stupid idea too. how do you plan on "hiding" something that has to run off the crank, and has to force air thought the intake?