what motor is it again? I think i remember H22, but i'm not sure.....
As for the first thing i would buy.....what do you want to set as your power goal? Are you keeping AC? What do you plan on spending total??
There is no point in dropping $400 on a manifold now and then having to skimp on other things later. I would first plan out every step you're going to take and then slowly buy parts as you find them. If you're in a hurry to get parts, you'll end up spending $200+ more than you expected in the end. I waited and waited on parts and ended up getting a deal on a NEW Exedy clutch and ACT fly....its normally $650 for the set up and i got it for half price.
Just start out making a list and then we'll go over it a bunch of times.....then you can start buying stuff.
Patience.....