The Harvest King flour is sometimes sold as "Better for Bread" flour. In fact, the last bag I bought, just recently, says both "Harvest King" and "Better for Bread" on it. It is a General Mills flour.
I personally feel that a pizza screen is the best substrate to use for baking Randy's American style pizza, although Randy has indicated that it is possible to bake the pizza on a pizza stone. My main reservation about using a pizza stone is that the high level of total sugar in Randy's recipe is close to 10% which, in some ovens, might lead to premature browning of the bottom crust. So, I will defer to Randy on that point since I don't recall making one of Randy's American style pizzas on a pizza stone.
I would not use an "air bake" or other pan for Randy's American style. The air bake pan, if it's like the ones I have (light colored aluminum), may not produce enough bottom crust browning, and using some other pan is likely to produce a different product from a texture standpoint than when using a pizza screen. Of course, there is no harm in trying a pan, or even a pizza stone, until you get a pizza screen. So long as the pizza bakes up properly, it should still taste OK even if it is not a proper American style. However, if you use a pan, it should be dark in color and be able to take a temperature of around 475 degrees F without having a coating (if it is a Teflon-like coating) break down and emit noxious fumes.