Welcome aboard, Rebecca!
The Disney Dream offers three pools to enjoy: Quiet Cove Pool (for adults only), Donald's Pool for families, and Mickey's Pool for the little cruisers! Those young ones, like your son, who are not potty trained are not able to go into those pools, but there is a fabulous area just for them!
Nemo's Reef is a huge splash area for little ones on the Disney Dream. When my kids were little, the adored all the pop geysers and splashing fun. There's even a tiny slide down Mr. Ray that the kids can ride when they play in here with Mom and Dad. Honestly, I kind of miss being able to go play in that area now that my kids are older! It's so bright and colorful, and it's all closed in with glass, so your little ones will not be able to wander off without you. Disney created the perfect water play place for its tiniest cruisers!
You're welcome to bring unopened prepackaged formula off the ship with you, yes. And your son is very much welcome at all of the family shows and main dining restaurants onboard. The servers that will travel with your family from restaurant to restaurant throughout your rotation are absolutely fabulous with kids, so he'll be well entertained and well fed. He will especially love the theming and fun that takes place when you dine in
Animator's Palate. If you'd like to book a night for him to enjoy the great programming with counselors in It's A Small World Nursery, you can do that when your window for online check-in begins, 75 days prior to setting sail. You may want to enjoy one night where you and your husband have dinner alone, either in your regular rotation in the main dining restaurants, or at Palo or Remy, the two Adult Exclusive Restaurants onboard. I hope that helps as you continue planning, Rebecca!
Marcy