I always use anti-seize, just don't get any on the end of the plug so that it gets into the chamber. Also use dielectric grease on the boots so that they'll come off the plug without tearing the wire apart.
I run NGK TR55s, I've found them to be better than the platinum the car shipped with.
I have run both the Denso and the NGK Iridium's and haven't been able to tell the difference. I have dyno pulls with both brands installed without a problem although I didn't change plugs while on the dyno to see a difference. My car runs very smooth with both brands. I pulled the NGK's out and installed the Denso's in the Vette and put the used NGK's in my 5.3 truck and it ran very good. Much better than the stock plugs. I for one am very satisfied with the Iridium Plug.