How can I make and store multiple pizzas before a potluck?
If you really want to blow them away, the best option is to cook them on-site, at least partially. If you can prepare and partially bake the crusts in advance, the rest of the process won't take as long to cook and the results will be better. 

If that isn't practical, 2 hours is a long time for the pizza to sit out before you transport it to a party where it will sit out even more, especially the one with chicken on it. Refrigeration would be a good idea. 

You may also want to try your recipes in advance and see how well they hold up to reheating.

I've had reason to make large quantities of personal pizzas in the past and found that making the crusts in advance, freezing them, then at the time of the party baking with the toppings to heat it and cook the toppings worked well.

As for the transportation question, if you don't use pizza boxes to transport them, do you have some other way to keep the pizzas from getting smashed up and sticking to each other? This is another thing that will probably be easier to manage if you assemble and bake the pizzas at the party instead of transporting them fully prepared.