I don't have any specific recommendations for insulation, so get whatever is cost-effective for your situation. If you have to, you can always go back and upgrade your insulation if need be.
I do have some advice with electricity however. I'm not an electrician, but I do know that you don't want to go over 80% of the load capacity for a circuit because you will risk a fire. For a common 15 amp circuit, that means you do not want to go over 12 amps on that circuit.
You can find the number of amps you are using quite easily. Amps = Watts/Volts. For a 15 amp circuit, we don't want to go over 12 amps, but how many watts is that? Well we know we have 12 amps and 120 volts because this is what most household electrical outlets have (with the exception of 240 appliance outlets). So that's 12 = W/120. 12x120 = 1440 watts. A 20 amp circuit's max load would be 1920 watts, and a 30 amp circuit's max load would be 2880 watts.
That being said, you may at some point want to pony up a little extra cash and have an electrician run you a separate 30 amp box if you are building in an external building without power, or installing a dedicated 30 amp circuit in a room which is attached to an space which already has electricity. Whatever you do, don't just swap out breaker switches, such as replacing a 15 amp switch with a 30 amp switch without upgrading your wiring; this
will cause a fire.
Anyway, I hope my long-windedness has been helpful.