What does a supercharger kit do? Why buy a supercharger?
A supercharger is a form of forced induction. Superchargers offer perhaps the most dramatic increase in horsepower to your truck of any aftermarket products. By compressing the air, it lets the engine stuff more air into a cylinder. More air means that more fuel can be stuffed in, too, so you get more power from each explosion in each cylinder. A supercharger's power supply comes from a belt that connects directly to the engine. It gets its power the same way that your water pump or alternator does.

Does a supercharger kit come with everything you need? Or is there a pre-condition my vehicle needs to meet in order to be able to handle a supercharger kit?
When purchasing a supercharger setup they are vehicle specific which means it will come with everything needed for a direct bolt-on. If you're looking to up the boost past the stock 6 to 8 psi that it comes with stock other modifications will need to be made.

How do you install a supercharger?
Superchargers are vehicle-specific, and they will come with everything needed for a direct bolt-on.