They do fit Iridium in the factory, and, yes, the interval is 75K.
I had them changed on our 2009 car at 6yrs old, which equates to 75K on the 12.5K annual interval even though the car had only done about 30K miles.
Our 2014 car is looked after by a garage that spun out of one of the canned Honda dealers - car has done 55K and they're absolutely adamant that the plugs are good for 75K regardless of age. Mind you, they don't seem to like doing stuff - I asked them to change the front pads and discs at the car's service a couple of weeks ago and they said they're fine for now!