If i order that exact one, will i have to buy anything else? Or does it come with everything?
You need control towers, landing pads, load bars and snowboard/ski clamps.
You'll have to do some research into what will fit your year of subie... or go to the shop and make them do it for you
I got some of my gear 2nd hand off craigslist, and the landing pads from rackattack. It took a while rounding it all up, but I saved a bunch of cash.