Hi Daniel,
Mark is right on the Full Service but normally I expect that is done straight after you buy a car, if its not been done very recently, as it gives you the clean base to work from.
I'm no expert so your questions might be better in the forced induction thread on the main forum.
IMHO - as for ECU's it;s what your tuner reccomends, as they are comfortable with what they know, that will get you the best results.
I run a Haltech, others Autronic, alot of Power FC's and some Microtechs.
Which shop to go to maybe you next question and I can't answer that one either as I dont use locals.
Check out the thread at the top of the ACT main page. See everyones thoughts and then make your own mind up.
Personaly I use Croydons in Sydney because they built my engine and installed my Haltech.
Cheers
S!N
If your budget doesnt alow then look at the advice above "you will need to get an RB20 or 300ZX ECU to get Nistuned". Most cost effective for a 33.