I have 2 children they are 17 months apart. I took each of them to WDW before they were a year old.
I took my son for the first time when he was almost 120 months old. It was in August and it was hot. He wouldnt drink his milk in the parks during the day because of the heat. I wound up giving him lemonade and water. I was always onthe go with him so i already had a compartmented storage container for my powdered formula. They sell these at babies r us and some toys r us.I took empty bottles inot the park and used bottled baby water. If i didnt have baby water i used any room temperature bottled water. The baby centers are hosted by carnation and have carnation formulas. ( at least they did and were the last time i was there)
I took my daughter and son when she was about 2 months old. I wanted to take a vaccation before going back to work after my maternity leave. I only gave her formula because she was soo young. I did water it down at times so she would take in more water. I took her in June and it ws also hot. I also breast fed her at times and used the baby centers for nursing.They ususually dont allow strollers in but since i was traveling alone with 2 babies they let me bring in the stroller. The nursing rooms are really nice. They also have highchairs to feed solids there, and a play area for slightly older kids to keep them occupied.
If your little one is eating solids then i would suggest you bring either the glass jars or the new plastic contaiers that gerber has. I used to get allthe differnt brands of baby food for my little ones based on the ingredients and what they had already eaten. I woudnt try too many new foods on vacation in case of an allergic reation. If they are only eating baby cereal then take some of that in small contaiers with you and mix with water in the parks.
Personally i liked the cereal inthe jars premixed with a fruit because they are convient. Both of my kids really liked the tender harvest bannas and peaches with oatmeal from gerber.
Babies r us and toys r us have or at least had a carrier for your spoons that fit 4 spoons in it for travel. Dont forget to take a bottle brush to clean the bottles. Avent makes on with a reusable cover. ( i used that on my last trip a few weeks ago to clean my sippy cups)
I like the pampers dispoable bibs instead of always using hte ones that you have to wash. I would pack extra wipes insteead of a wet cloth.
I see you have other kids, what type of stroller do you have? do you plan to
rent a stroller for them in the park? I kist got bakc and i took the kids who are now 2.5 and almost 4 and they both spent a good amount of time in the stroller ( a double). You may have a problem with the middle child wanting to be carried or in hte stoller iwht the baby if you dont watch out.
Since you have the stroller and older kids i would invest in a smaller cooler and get water for the parks. I did that and i had no problems bringing it in with me.
My daughter went swimming for the first time when she was in florida at 2 months old. She loved it.