That's a lot of good questions.
"Skin" is a term of art used by pizza operators to refer to the dough after it has been rolled or hand shaped and stretched out to the desired size. It is the same thing as a "dough round". I don't think you will hear Neapolitan pizzaioli
tossing around the term. It's strictly a slang U.S. term.
I have combined the Caputo 00 Pizzeria flour with high-gluten flour before but that was for the purpose of trying to reverse engineer the dough made by Dom Demarco of DiFara's in Brooklyn. He uses 75% Caputo 00 Pizzeria flour and 15% All Trumps high-gluten flour, both by volume. Domenic does switch around his ingredients from time to time, so it is possible that he may now be using other brands (he used to use the Delverde 00 flour before he switched to Caputo). I know that member scott r routinely combines 00 flour with either bread flour or high-gluten flour to achieve the results he desires in his modified (clean cycle) oven. I have combined the Bel Aria brand of 00 flour with bread flour to increase the protein and gluten content, in an effort to simulate the Caputo 00 Pizzeria flour. That worked well for my purposes. But apart from these experiments, I have stuck with the Caputo 00 Pizzeria flour by itself. What I now strive for is to achieve a soft crust, even at the expense of sacrificing some crust color. Or I coat the rim with olive oil before baking and/or use the broiler element to coax more color out of the crust. If you push too hard for the ideal crust color, you will often end up with a more cracker-like or crunchy crust.
As you noted, I did play around with using things like diastatic malt, dried dairy whey, dry milk powder, and I even intentionally damaged the starch in the Caputo 00 flour (by running it through my food processor), all in an effort to get more crust color out of a finished Caputo 00 crust which, as noted above, has a tendency to bake up light in a home oven--and sometimes almost white. The experiments were a success and more crust color was produced but the color was not the same as you would get from baking a Caputo 00 dough in a high-temperature wood-fired Neapolitan oven. You will clearly see the distinction if you compare the photos of the pies I made with some of those posted by pizzanapoletana (Marco) of the real deal. I also discovered that the texture of the dough is affected by these additives. I thought the doughs handled better with the dried dairy whey, for example, but I think the whey also affected the texture of the finished crust. There are tradeoffs when using the additives. They do what they are supposed to do from a chemistry standpoint but they can't make up for basic oven deficiencies.
As for other uses of the Caputo 00 Pizzeria flour outside of the Neapolitan rules, I have used it with success in making doughs for deep-dish pies. I have tried using both a natural preferment and commercial yeast (instant dry yeast). You can see samples of my efforts at this thread: http://www.pizzamaking.com/forum/index.php/topic,2365.msg20625.html#msg20625
. I thought the pies were elegant, mainly because I used some of the finest ingredients available. To the best of my knowledge, Neapolitans do not make deep-dish pies along the lines of our domestic Chicago-style deep-dish pies, so it was fun exploring its deep-dish potential. You can also use the Caputo 00 Pizzeria flour to make bread or rolls, although I have not done so. I believe that scott r uses the Caputo 00 Pizzeria flour for all kinds of pizzas, including bar (pub) pizzas, so undoubtedly there is greater flexibility in using the flour than we have come to believe. I would place the Caputo 00 Pizzeria flour roughly between pastry flour and all-purpose or bread flour, so applications that will benefit from that strength of flour should be fair game.