About your heat question. Yes, there's heat and there's heat. Gas is a liquid and thus produces a more moist heat. This becomes barely noticable in a gas-fired stone oven like a Wood-Stone, however, in a metal deck oven--even if it has stone decks, the metal which is not absorbtive will contribute to more moisture in the oven. That's why putting tiles in your oven improves the heat quality of a home oven. All stone ovens that are fired by wood or coal provide the most dry type of heat.
I always test ovens wood-fired and gas alike with the same recipe formulation so that I can see how the crust performs with the different technologies. The very same crust that has a very fine, crackling crisp outer crust and well developed open-holed crumb in a wood-burning oven or coal oven that cooks at 4 minutes (12 inch pizza) or under, will have a decidedly thicker outer crust that is chewier and more crunchy crisp than the wood or coal. The crumb still develops well in both. When you cook the pizzas side by side, you can actually hear the difference in the crunch when they are being sliced. Why? One: moist heat forms a moisture field around the dough as it bakes which does not penetrate as quickly into the crust as dry and therefore creates a harder thicker outer crust. The pizza generally takes double the amount of time--or more to cook at the lower deck oven temperature which gives the crust a "breadier" consistentcy. Few deck ovens get up to 700 degrees on a consistent commercial level (ie during peak times), so at an average temperature of 650 or 600, the pizza will come out wonderfully crisp and light inside and just a bit more chewy--and in some cases, a lot more chewy depending upon the formulation. Lower temperatures will perform well too, but really, not under 500 degrees.
As for steaming, Bread baking and pizza are fundamentally different, there are similarities, but most bread baking technology must be adapted to pizza--if it can be. Steaming is less for oven spring than it is for crust development. Bread cooks at much lower temperatures than pizza and has lots more time to develop in the oven. PIzza is wham bam. Bread bakes on its own and pizza has a topping which complicates its baking procedure. Steam would not be something applied to pizza.
Heat is a very fascinating and complicated subject, everything comes into play from the oven materials to the type of coal, to the type of wood and to the degree it is cured. Wood especially varies in amounts of BTW--some burns hot, but not sustained, and some burns hot and long, still others give off actual flavors. Even natural gas and propane don't cook the same.