NOS ruins pistons only when used incorrectly. Nitros Oxide adds oxygen into the cylinders. Too much oxygen and you can mess things up. That is why all of the higher output NOS kits are wet meaning that they put more fuel in with the NOS when you hit the 'GO' button.
I believe that kits under 50 hp don't require additional fuel (other than what the stock system will dump on it's own). Please correct me if I am wrong.
you want the electron blue pearl (aka civic si blue). i think blue is one of the best looking colors on treps. i will use buschman's pic of his car for an example, even though it is viper blue, but both look damn good IMO.