Q: Bootcamp help

I know how to make the partition but i am etremly nervous i will screw up. in simple words so i can understand, please answer the following questions. 1. Do i need to buy a copy of windows 7? and from what store? 2. How big is the usb drive needed to be to install the aplle server things? ( i dont even know..) when i get to windows, do i need to install a "microsoft hot fix"? can someone please help me? i dont know what im doing.

it says its 10.8.4 but idk if its moutain lion. Mac os X 10.8.4 wasnt there on the list.