I really like your motto about having fun on vacation. Stick with that!
I thought of a few other things that might help. I would definitely take a stroller, and I would suggest a stroller fan. Even though it won't be that hot in October, the sound of the fan is very soothing and helps block out some noise. Although they do have Mickey Mouse fans for sale, I would take your own, as they are sometimes sold out. (Also, I don't think they are quite as strong, therefore they don't block as much noise) Don't forget to take a screwdriver and extra batteries! Make sure you have a large enough plastic cover to cover it if it rains.
I swear by Melatonin, but would definitely suggest you try it at home first. (Just to warn you, it sometimes turns stool green, so don't be alarmed!)
I stock up on glow necklaces and braclets ahead of time. Having that extra little light source can be reassuring. I put them on the stroller at night, but also wear them myself during the day. That way, if we are at a show that gets dark, or on a ride that goes from light to dark, there is enough light so my son doesn't get scared, and he knows right where I am.) You might want to consider a small flashlight as well.
I have PECS for different meal options on a ring. When we get to a restaurant, I just take off the ones that are available and let him pick from those. I think the suggestion of making PECS for some of the different activities is a great idea too. Not only does he have an idea of what is coming, but he also has something to hold onto.
Another suggestion is pipecleaners. We take them on the plane, have them in the hotel, and will take them into the parks. They are soft, flexible and provide an outlet for fidgeting without getting messy. I stock up at the dollar store before we leave.
I hope this gives you some ideas. This is a great place for asking questions and getting many ideas!