I didnt read your whole post, but a small piece of advice i could throw in is make sure you get non projected spark plugs.

The projected style tipped spark plugs are more prone to detonation.
Ive never thoguht to run any of that iridum crap on a turbo engine nor would I try it. I just stick to NGKs and I run the BR7ES... Therefore they are non projected and one range colder than stock. If you were to get the BRP7ES the would be projected hence the P.
If running say 20+ psi the gap that works best for me is between .028 and .031, you generally want to get the largest gap you can before the car starts missing in higher rpm and boost pressures.