Well, to start off, you could find most of your answers if you browsed the nitrous forum, but i'll tackle as much as i can for ya.rony said:
There's a bunch of different ways you can go. First you have to decide what type of kit you are going to get. you have to consider all the different factors though. when are you planning on running that 150 shot? if youre going to be running it soon (like within a half a year or so) then you should wait till you have your motor built up, and then go direct port. or, what i would suggest, is buy a dry kit right now (i prefer zex, you can get one for $435 at www.evanshondaspecialist.com ) and run a 55-65-75 shot. Our stock blocks can handle up to a 75 shot without a problem. Then you can get used to the nitrous, get a feel for what you want, if you really want the 150shot etc. Then if you decide to go with the bigger shot, sell your dry kit and go direct port (After you build up your shit first) Nitrous LOVES high compression, so higher compression pistons = dope. I'll see if i can make up this list of what you need for each shot:
50-55 shot - 1-step colder spark plugs
65 shot - 1-step colder plugs & retard your timing 2 degrees
75 shot - 1 step colder plugs, retard your timing 4 degrees, probably time for an aftermarket clutch too.
anything above a 75 shot, and youre going to want to start building up your block (in my opinion, some people spray 80-100 on the stock block). you will DEFINATELY need to ugrade your fuel system: pump, injectors, etc. youll need a new clutch, plugs and all that other biz.
You could just start out with a direct port kit, but the problem is its actually not that safe to run the lowest shot possible, because the jets are so small. with most dry kits, you have one nozzle that sprays into your intake. with a direct port kit, you have a nitrous/fuel mixture sprayed into each cylinder through your intake manifold, so you have a more evenly distributed mix. But, say youre spraying an 80 shot, thats a 20 shot per each nozzle, and that means the jets are like microscopic. if a little particle of whatever gets in the way, its gonna screw up your mix.
One of the main things you have to worry about with nitrous is detonation. You dont want to be running lean. the zex kit is the safest among dry kits because you run a little bit richer than the others (safer = smarter) remember safety should come first, you dont want to blow your engine. There are also some rules you need to know about. Dont spray for longer than 15 seconds. Dont spray under 3000rpms. Dont spray at really high speeds. If you let the temp get too high, youre going to melt something.
The Zex kit is great. It's very very easy to install. You CAN and WILL install it yourself (its that easy). It is inexpensive (if you get it at the right place. And its safe. As long as you have colder spark plugs (you can get the zex plugs, or ngk's one step colder) and the proper engine retard, you can spray all day and all night without worries.
I guess a lot of what you should do depends on how much money you have. reply back with some more details on what you want, and any questions you have. my post is getting too unorganized to keep going.
peaces
anyway... i don't even have the car yet... but i want to know as much as i can of what could go wrong, how to avoid, etc , etc.. what i really want to do is be fast all motor, as fast as possible actually.. but have the juice as a "just in case" you get me? thats why i don't really know what way to go because i don't want to do some crazy shit like go FI with a turbo and then have the n2o... you know? all motor is good but if somebody creeps up slipping a finger will do the trick.. maybe i'm talking out my ass and that wont be too possible... the 150 shot can wait... i just want to know what needs to be reinforced so i don't fuck anything up... detonation..? BOOM? don't really know much about nos 
