The dining plan is based on the number of nights you are staying so you will have to purchase the dining plan for 3 nights for everyone 3 years or older in your room.
For the package (room + tickets + dining plan) you will have to purchase at least a one day ticket for the 2 adults and the 5 year old.
The ADRs you have listed require 5 TS credits. If you purchase the regular dining plan (1 TS, 1 CS, 1 snack per night per person) you will have 3 TS credits. If you purchase the deluxe dining plan you will have 3 dining credits per night to use at either TS or CS. Right now you are between the 2 plans, but unless you plan more TS meals you will probably be better off paying CRT out of pocket.