Pretty much everyone is on point about the info. Bottom line, most kits come with everything and its intended to be used on a stock Mustang. But most of them come with the fuel managment system (injectors etc) and a tuner to reprogram your computer.
SC's are blet driven, meaning the belt turns the impella. THe turbo is driven off your exhaust fumes... that's why you get that "turbo lag", meaning its like a split second to kick in after you punch it.
But if you plan for it to be a daily driver and you really not going to put in in the race track etc. Basically any aftermarket kit will do. But if you are not familiar with working around the engine, I say pay the extra 700-1000 dollars to have a professional to install it for you. Its better to be safe than sorry.
But either way, turbo or SC makes a ton of power and its a lot of fun to have.
I too will be adding a power adder by Febuary next year, so good luck.