As stated above a window switch should be mandatory for a nitrous application especially if its a manual transmission.
If you want it to get the most out of the kit then you should get a bottle heater and a purge kit. If you can only get one then get the bottle heater. The heater the I have is pressure controlled so it maintains the pressure right at 1100 psi. They are usually adjustable so you can change your pressure set point.
I have never had a zex kit but my Trickflow wet kit came with all the solenoids, jets, hoses, WOT microswitch, bottle and a switch for arming. I purchased a bottle heater, purge kit, window switch and a autometer pressure gauge separately.
At a minimum I would get a window switch, heater and at least a tank mounted gauge.
I ran the stock plugs with the gap closed up a little bit for the 50 shot and then dropped to one range colder when I went up to 100. And don't for get to back the timing out 2* for each 50hp of nitrous.