Do alot of google and youtube research. I did most of it on those. Everything from how you want your car to look like all the way to what performance route you wanna take. I spent sleepless night doing so...lol. researching is the fun part.
Side skirts are easy to find. The Modulo front lip are usually modded to fit. Nothing for the rear. Unless you get a 2012 rear bumper non-si, theres a kit for that.
I've been doing the same research for a good month or two before deciding on the same wheels too. i couldn't be happier with 17x9 +35. You may or may not need to fender roll depending on tire size.
i have an exedy stage 2 w/lighten flywheel. idk if its the same, but my experience with it is, more feed back, little more chatter, grabs harder, and the friction point is lower. stage 2 is more for ppl that are forced induction. The stock clutch can hold up to 300hp.
my only advise is if you want to get that big mod, focus on that mod and try to avoid buying the little ones. if you do, it only makes it that much more difficult to reach.