There are no kits that bolt directly up for Mark Vlll's. Did you decide what type of SC you wanted?
Well I would like what ever is cheaper!
I do not know anything about superchargers, but if I was going to do it I would not go for cheap.
No. If you do you will need cobra heads, upper and lower intake, throttle body etc. etc.
IMO Vortech is the better way to to as far as $ invested. You can get nice kits used for about $2k.
If you want to go new for a decnet kit plan to pay $5k+ just for parts.
You need to search around on some mustang sites as well as some others and you will find the answers you are looking for.