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.

At a minimum you will need pizza boxes. See if you can get 6 from a local pizzeria. He may be willing to sell or give them to you. If not, they can be bought online fairly cheaply but you may have to buy 50. An insulated pizza pouch would help too. They come in different sizes. I am sure you could find one that will hold six pies. Don't forget to put parchment paper under the pies. Don't use paper towels!

350 is low for making pizzas. Most home ovens only go to 500 and that's not hot enough. Getting a pizza stone will help some. An oven that's 800 - 1000 degrees would help as the pies will cook much faster and have a crispy crust. If you add lots of toppings, the pies will be wetter and take longer to cook. 350 is OK for reheating but for the main baking the low temp may hamper your results.

You can roll out your doughs and pre-toast them in the oven. Cook them just long enough to bubble the dough but not enough for them to start browning. The result will be a "crust" that's like a soft tortilla. It will be easier to work with and somewhat stack-able but but parchment paper in between each dough.

Make all your sauces, cut up your cheese(s) and all your other topics before you start. Have everything ready to save time. You want to minimize the amount of time between your first and last pizzas coming out of the oven.

If there is an oven at your destination, you could under cook the pies a little and finish cooking at the potluck. Be careful not to burn the undersides of the crust.

Going overboard on the toppings will mean the pies will take longer to cook and you'll get more liquid runoff inside the oven i.e. more smoke and mess.

I am not familiar with the specific types of pies you're making but I'm guessing they're thick crust or deep dish.

I make mostly thin crust, not Neapolitan but close. I always make my own sauce and dough using slightly modified Peter Reinhart recipes. Making your own dough...I recommend doing a three day cold rise. It gives the dough more flavor. That's why the dough from some pizzerias tastes like cardboard. 1 day minimum. If you decide to do that, you need to account for that in your prep time. You can buy pre-made in the store, either frozen or kinda-sorta fresh i.e. refrigerated but not frozen.

P.S. Once the chicken is cooked through, the risk of salmonella goes away. I have not used chicken as a topping but my thought is you shouldn't be putting raw chicken on a pie. It should be cooked before hand.