See our tours of the parks for all the great rides and attractions very young children can enjoy at the WDW parks. We have heard from parents that visitors with very young kids should skip Islands of Adventure. My family had a great time. Part of a trip to WDW is about building family memories, and it would be incomplete if the whole family wasn't there. Sheryl's friend will have the advantage of having Sheryl's family with her.
Last recommendation is to take or rent cell phones or walkie talkies.
The range of the walkie talkie is the entire state of Florida, and if you are using that feature, you aren't charged for minutes. She loves fish. I would have to say even a 2 year old can enjoy Epcot as well as the other magic that Disney creates. The new strollers at the Magic Kingdom, Animal Kingdom and Epcot are hard. Put a blanket in the stroller so that it is more comfortable.