Brad, which 'highgluten bromated flour' did you buy? Does it have a brand name?
Your biggest obstacle, by far, is your 500 deg oven. A 500 peak temp (with a longer bake time) pretty much guarantees a dense bready crust. A more conductive stone will help reduce your bake time a bit, but there's no stone on the market (at least not yet), that can, at 500 deg., bake a 4-5 minute NY style pie, which is where you want to be for great oven spring and a puffy chewy crust.
With a 500 deg. oven, you have no choice but to try an oven trick.
Here's how I'd approach it:http://www.pizzamaking.com/forum/index.php/topic,11783.msg109285.html#msg109285
Using a frozen towel, you should have no problem hitting 600-650. The actual temp you want to go with will depend on your stone. Tell us a little bit more about your stone. Size? Thickness? Brand? If you don't know the brand, describe it or take a photo.
Once you start covering your thermostat, you will lose it as a temperature gauge. If you don't have an infrared thermometer, it's time to get one. They have used thermometers on ebay for $20.
What thickness factor are you working with? From the photos, it looks like you're working with way too much dough for a pie of that diameter. Having a 500 deg. peak temp is bad enough, but too much dough is the kiss of death for oven spring. Post your current recipe (actual quantities in grams, not percents) and diameter.
Screens create air pockets between the pizza and the stone, which, in turn extends your bake time. Lose the screen, buy a peel and use it.
It's going to take some to master skin forming, especially with less dough. Flour and yeast are pretty cheap. Make a lot of extra dough balls and use them to practice stretching. Here's a good video (ignore the rolling pin stuff).
The goal should be a very thin, somewhat even skin with only a slight taper towards the middle. The middle always has a tendency to thin out, so you have to actively work against that as you form the skin. The larger rim doesn't come from forming but from oven spring.