I'm stopping by a local store today to buy some of that fuel injector cleaner, I just got a foldor to keep in my car, i'm going to put every docuemented reciept and note in there as I change oil, clean the fuel injectors, and any mods I buy.
I may or may not buy that air filter because I still plan on a CAI, and if I buy a 45$ air filter , one comes with the CAI, so I don't see the point, rather than having one until i get the CAI.
Focaljet will be of great help to you. A cheap suspension route would be to swap in the SVT suspension (slighly lower ride height, better shocks, etc.) unless you're going for the hardcore lowered to 1/2 in look.
You could go the cheap-o route and heat the springs with a welding torch and let the car's weight compress the springs, and when they cool the car will be lower.
For the record, heating and/or cutting springs is the worst idea ever. It will make the car bounce and handle unpredictably and will hurt more than it helps. Unless you're a ricer.
As for the K&N filter/full CAI, get a CAI. Trust me.