you cant use intel cpu with amd mobo so you have to buy a new mobo.
You probably do not need the i7 as I assume you are bulding this rig for gaming, buy the i5 2500k instead.
You do not need more than four gigs of ram, but people typically buy 8 gigs in 2x4gb format as it is so cheap.
I would not buy open box mobo.
I used to use it just for gaming, but now i often work with semi-pro video editing and stuff.
I know about the open box, i just posted an example, but i'm buying a close box indeed.