NO2 Questions from a beginner

[91LX2Bfast]

In terms of bottom end damage, just as 04S/CStallion said a wet kit is safer. But considering you have a '00 GT, with a wet system you'll have to worry about fuel puddling in your intake manifold and causing a backfire that'll blow the manifold to pieces. So you'll find that a lot of racers who run wet kits eventually switch to the aluminum Bullitt intake. Another non-dry option is the NOS noszle kit. Its actually a direct port setup, but it is a pricey kit.
I know a fellow that has been running a 125 dry shot (Zex kit) on his non-pi 4.6L motor while at the track for years with no problems. He has an upgraded fuel pump, adjustable FPR, and runs a little high octane gas. Given that, I don't see a dry 75 shot being a problem on 93 octane. I would run one step colder copper plugs for up to 75 shot, and 2 step colder for 100-150.