[Jared at Pelican Parts]

Basically, the only advantage to iridium plugs is that the electrode lasts a really long time.
I doubt you'll notice any difference in how the car runs (unless the current plugs are badly worn)

I imagine the Autolite plugs will work fine, however I prefer to use Bosch or Beru in Porsches.

Don't put any anti-seize compund on the threads.