"I've read about people freezing their homemade dough. Is there a proper way to do this? If you were doing a cold ferment, at what stage would you freeze it? What's the best way to thaw the dough? I'd sure love to be able to cook a decent pizza on a whim."
Great question, and the answer is pretty simple. You can freeze a homemade dough at essentially any point in the process and it'll work just fine. In terms of the gluten structure and the interaction of flour and water, freezing has no ill-effects. Unlike, say, freezing a steak or vegetables, in which water trapped inside individual cells can crystallize, causing those cells to rupture and spill liquid upon defrosting, pizza dough has no cells in this sense, thus ice crystal formation is not a big deal.
As far as yeast is concerned, they're perfectly happy to take a nap in the freezer for a little while. As with most tiny organisms, their activity is largely dependent on the temperature of their environment. At higher temperatures (say, in a proofing oven), yeast becomes wildly active, reproducing like mad, and consuming sugars like it's their last meal on earth (it is). Chill them, and their activity will get slower and slower until, when you finally freeze the dough, they utterly stop, becoming inert until you defrost them again.
It's not just a question of slowing their metabolism. Freezing dough also performs another essential function: it prevents yeast from reaching its food source. In a ball of dough with liquid water, yeast can't exactly travel freely, but the dough is still liquid-y enough to constantly expose hungry yeast to new food sources, allowing the dough to continuously ferment and evolve. Freezing will completely halt this process.
So what's the best way to freeze dough? Well, seeing as freezing is something you do for the sake of convenience, it makes sense to freeze dough as far along the process as possible, so that when you are ready to bake, the work required after pulling it from the freezer is minimized.
When I make extra dough to freeze, I'll let it perform its initial fermentation (including a cold ferment if that's in the recipe), divide it into individual balls as if I were going to allow them to go through their final proof. But rather than proof them, I'll stick them on a plate or a rimmed baking sheet lined with parchment paper and toss them in the freezer. Once completely frozen, the balls can be thrown into a zipper-lock freezer bag.
To use them, I pull out as many as I need and allow them to proof as normal (either in an oiled bowl covered with plastic wrap, or on a floured wooden board, covered with a floured towel or plastic wrap), tacking on an extra couple hours to allow them to defrost before they really start to rise. Is it INSTANT PIZZA? No, it ain't, but if you're the kind of person who prefers to work in large batches, it's a great way to save yourself from having to lug out the mixer every time you want a pie.