Don't rely too much on a dyno shop helping for just a dyno tune if you don;t buy the kit from them. They'll dyno your car and tell you what your a/f is but most likely the information stops there unless they are nice guys. Best to familiarize yourself with nitrous a little more as you'll be in charge of troubleshooting, maintenance, etc.

Most nitrous jets are rated for a nitrous pressure of 950-1100 pis. Best to find out what jet recommendations your kit offers. So basically if you do plan on getting a heater right away set your tune for the pressure range the heater works at.