I agree that the pizza looked frozen or unappetizing due to the stiff crust but: 1. It was more a demonstration of the oven. Does he have to create a dough just for that, esp when he has company coming over? 2. He says later that he can’t get his homemade dough to slide off the peel well so that’s why he used that…

There are ‘firebricks’ used in pizza ovens that you could use as well. I imagine they are ‘food grade’. Some bricks are concrete, not clay, and those might give off fumes and should definitely be wrapped.

No, that’s not correct. You heat them all up together otherwise the cold stone on the hot grill is likely to crack. Stoneware should be started cold and brought up to temp, all the pieces at once.