I am gonna move this to the 2.2l section. There are many post in that section covering mods for this engine. You can also get more answers to your questions there.
But here are a few things to get you started.
These are some basic bolt ons.
Cold air intake: STS, Volant or K&N are the ones I like. There are others too.
Electric fan: Summit has kits for our trucks. You can also save some money and find one that will work out of a junked car.
Pulleys: I like the STS ones.
Header: The ALS are good ones.
Exhaust: Flowmaster or equivilent.
Performance chip: Jet chip.
Better plug wires and plugs: autozone, pepboys or similar.
Then you can get into some of the more radical add ons and internal mods.
Turbo: Mach performance.
Ported head
Roller rockers: summit
Stroker and cam kit: there are a couple of sites for this. can not remember which ones.
High output coilpacks: summit