Not sure I would consider these rules but behavioral expectations and a few tips. When we get to our destination (not just Disney, we do this for all family trips) we take a picture of each child near the entrance. That way we have an accurate record of what they are wearing that day, in case they get separated from us. Much faster than trying to explain what they look like. And it makes a nice picture too.
Remind little ones not to tug on character costumes, tails, hair, etc. Also to keep back from the "fur" characters until they are aware of your being there. They can't see very well right below themselves.
Teach them how to identify a cast member and practice with them how to ask for help. Cast members are trained to help lost kids and will know what to do if that happens with your family.
Pack some snacks but also plan for treats. Hydrate often. If they are not taking their normal amount of pee breaks they need more water. Florida is stinking hot.
Rent a stroller. They may have outgrown baby strollers but they will be grateful to have a place to rest. Little legs can only make it so far.