Just read over this whole thread. glad to see you are addicted and jumped in with both feet. I am too addicted, and it is so worth it, everytime i put the smack down on BMWs, porches and STIs all with my 130hp. I have a full prepped FSP car.
with regards to a cordless impact wrench. i use one, but it only has about 80 lbft or torque. ie. not enough to break the bolts free. So i have to crack them by hand, use the wrench to zip them off, and then back on to about 80lbft. lower the jack and torque to spec by hand. works well, i can do all 4 tires in about 10 minutes if i really hustle. (o ya, i do 2 at once, jack one whole side of the car up.)
if you are looking into getting one, i would recomend a Li-ion or Ni-MH battery so u dont wear batteries out (one of my Ni-Cad batteries is perma-dead). I would also recomend 150 lbft or more, so u can remove the step of cracking the bolts by hand, then just be careful when using it to put the bolts on.
for auto-x: '04 Liquid Grey ZX3
for street: '02 Infrared SVT