- My S/C came with new plugs. They are NGK's and supposedly just one heat range cooler than stock.
- The blower should already have the proper amount of oil in it.
- I have looked into a cooler T-stat. The T-stat for the 3.5 motor is actually a whole assembly and costs ~$25. A mechanic at my dealer says that the stock T-stat opens at around 175 degrees and he didn't know of any american Isuzu engine that ran a cooler T-stat.
- I would run the breather back into the intake like indicated in the instructions, then you're not violating any emission laws.

Good luck on the install!