Welcome to the Disney Parks Moms Panel Kathleen ~
It sounds like you have an exciting trip planned and you'll be dining in some of my favorite locations. There is no set dress code for any of the restaurants you've selected. Cinderella's Royal Table and Be Our Guest Restaurant are inside of the Magic Kingdom and as long as you are dressed properly to enter the Magic Kingdom, you will be fine in both of those.
A lot of people dine at Chef Mickey's before or after going to the theme parks. As long as you are dressed appropriately for a theme park, you will be fine in Chef Mickey's.
For the Pirates and Pals Fireworks Voyage, theme park casual is fine too. Some kids get into the spirit and dress like pirates for the voyage.
The Pirates League in the Magic Kingdom is a fun and popular option on the day kids plan to sail. I know you are going to love this voyage.
Please feel free to visit with all of your planning questions. We're hEAR to help!
Wishing you minnie magical memories :-) Allison V.