First off, pulling off a track/show car takes lots of money. Walls, rumble strips, going off track, curbs, you name it have been known to rip off front bumpers and sideskirts. So you may want to consider your goals/ideas in this matter.
But as far as your list goes, I think it would be easier to just go with one brand aero. I would suggest Origin lab or version select(
www.tougefactory.com,
www.i-m-racing.com), as they have what your looking for instead of trying to mis-match a kit togather. For the S15 front your going to need S14/S15 hood hinges and a S14/S15 front radiator support also.
For a track car you are also going to need a few more suspension pieces(
www.splparts.com) and I would just go with a set of Megan street coils instead of paying an arm and a leg for the tanabes. This is all just my opinion though.
