Before you even start going through any big modification process I say you spend the next month or so reading as many threads on this site that you can because you are very limited in knowledge (hell we all were at one stage) and If I was you I would try to get as much knowledge under your belt before you go down this road so you don't waste money.
The first year that I had my car I didn't do many modifications (was still in year 12 and had no cash) but I spent nearly ever night reading and researching what everything was and what parts did what. Best help I ever had was SAU, I suggest you use it to your advantage. All the information you could ever want is on this site so just have a search for it.
Not sure what a Z32 AFM is? Spend a few hours searching it and reading, then you will know one extra thing.
Not sure what the benefits of an aftermarket ECU are? Same thing, start searching brother.