Some of you nitrous guys are dumb. On a newer ECM you don't need a nitrous tune and a N/A tune. It's really simple.
All you need to do is wire in a relay and a resistor to the IAT sensor to the hot lead on your nitrous solenoid, that way whenever the nitrous kicks on the IAT table in the tune reads a false (High) number. All your tuner needs to do is pull the 4 or 5 degrees of timing out from that value in the IAT table and bam!
You now have a nitrous capable EFI vehicle that doesn't require re-tuning for N/A or FI, whatever you're running. You just gotta set your fuel jet right.
As for plugs, a 7 series plug is ample. Remember, NGK does their heat ratings backwards. The higher the number, the COLDER the plug. Also, a non-projected tip would be very beneficial. To reinforce this, a very experienced and well diversed Nitrous friend of mine runs a 7 up to a 250 shot, and bumps to an 8 for 300-400 shot. Drivability begins to suffer from lack of low end/low engine speed torque, but after the 300 mark, you really don't see too many people using that on the street.
Also, since FI (blower temps) get pretty warm and can skew the output, you can wire it to the ECT sensor and make it do the same thing. If you do that, the Coolant temp gauge will move and that gives you a visual signal to let you know that timing is actually being pulled.