I didn’t read through all the replies because I couldn’t deal with how many people were getting onto you about the bathroom rule

Here are my suggestions on rules/boundaries for the Disney trip:
-discuss what to do when you get lost. Point out what cast members look like (look for the name tag) OR find a mom to help you. If your kids don’t know your phone number, you can write it on a piece of masking tape and put it on the inside of their clothes. My son got separated from us once a couple years ago (he was 7) when we went to park the stroller for his sister, and he thought we went into the ride. He found a cast member and stayed with her next to the ride he knew we were heading too. He did great!
-Being at Disney means we WILL be standing in a line. There’s lines for rides, lines for food, lines to have your picture taken. I set this expectation real quick to eliminate whining. My kids caught onto it and dealt with the lines well. We played Rock Paper Scissors, or heads up, 20 questions (must be a Disney character of course!) and other small games while we waited.
-let everyone pick 1-2 “must do’s” for the day.This way everyone is happy. Anything else you get done is just icing on the cake.
-Set a budget OR give each child a gift card for souvenirs and then STICK to it. It’s soooo hard to not buy everything but it’s also a good lesson.
-Take plenty of water/snack breaks. I usually kept a treat in my bag and when they did start melting down (tired, heat, long day, etc), I’d pull out those jelly beans or that lollipop and all was well!
-1 treat per day. Their choice.We packed MOST of our food in. We would eat breakfast at the hotel/home, pack in lunch and snacks, and then eat out a dinner meal if we were staying long enough. As passholders we weren’t often there open to close. That being said, each child got to pick a treat a day. Mickey bar, rice krispie treat, churro, cupcake...whatever they wanted. But only one.
-Be flexible. Rides will go down, melt downs will happen. Lines will be long. But if you go in with a good attitude and just have fun with it all, then it will be a good time with great memories made no matter what. I hope
You enjoy your trip!