I took my second son to Disney 3 times after I introduced the potty.
Honestly, if you bring all of the extras (bringing a special potty seat, covers, etc.), you may or may not need them. My oldest used a foldable seat; my youngest refuses to use them. It is a shame to put forth all of that trouble if you don't absolutely need to.
Ask yourself how far in training your child is. At one of our trips, my DS was fully trained at home but not on the go, so we used pull-ups while in the parks and tried to get him to a potty when we could, but didn't sweat the accidents. Later, when he was trained in the house and mostly successful out of the house, I brought pull-ups along as well as disposable seat covers and gave him the choice in the parks. He is 3 and half now and has been trained everywhere for a year. I brought a few pull-ups on our recent
Disney cruise but he refused to use them and was very diligent about using the potties everywhere. He was trained enough for the Oceaneers' Club, so underwear it is then.
I think offering choices is important, remembering that Disney is a really exciting environment, far from the routine, no matter how many contraptions you bring along. Be prepared for accidents, don't overburden yourself with accoutrements, and talk about it with your child.
The baby care centers are great, but chances are, they won't always be near when you need them for a potty stop. You can use toilet paper to cover the motion detectors. I really do think that for most kids, if you are nonchalant about the noise, then they will follow your lead eventually. I have a sound-sensitive son, and even he relaxed after lots of practice in public bathrooms.