I think I would do DHS at RD, and do Epcot later. At DHS I would get there about 1/2 hr. before opening, and go right to Toy Story Mania. Even if your toddler can't really hit many targets by pulling the string, the Toy Story scenes and interactive parts are highly entertaining, and fun for everyone. The only "spinning" is when your car turns around and slides down the track to the next screen. You can check it out on a you tube video if you want to see it. It is a great ride with long lines all day, so first thing is the time to go. Then you can across the way to the area where Buzz and Woody are meeting if you are interested. Then there is the Muppets 3D movie, The Little Mermaid attraction, Beauty and the Beast show, and there is a Disney Jr. Stage show if you are into those characters.
You could make your FP for Epcot later, and the toddler might enjoy the new Frozen ride if it's open which will probably be a Tier 1, and then you could use the other two for the Nemo ride and Turtle Talk with Crush. You could time your FP times around your meal if you are going to reserve one. The Frozen ride will be in the World Showcase area in Norway, and then there is also a cute boat ride in Mexico. The rest of WS is walking around looking at the countries. There are Kidcot stops where kids can color and get stamps from each country if that interests your toddler. There is also a model train display in Germany, and there are performers throughout the countries as well as characters that you can meet, and you can check the Times Guide to see where and when they will appear that day. But it is mostly more of an adult focus.
In Future World at the front of the park, you will have the Nemo ride and Turtle Talk(Crush interacts with the group). That is in the Seas building where there is also dolphins swimming in a tank, manatees(my fave!) and fish exhibits. There is a restaurant, The Coral Reef, where you can sit next to the aquarium while you eat. The building next to it The Land has the Garden Grill restaurant where Chip and Dale come around to your table. There are also Pixar shorts you can watch and The Character Spot where you can meet characters(selection rotates so you can check the Times Guide).