1. I didn't have to.
2.Aftermarket shocks help alot, so yes.
3. Highly recommended. I have Skunk 2 in the front. They work well but are a bitch to align and a little pricey. Ingalls in the rear are all you need. They are easy to adjust and relatively cheap.
4. Definitely. New tires are pricey and handling will suffer big time if your alignment is out of whack.
Good luck. Post some pics when you are done.