If your kids are enjoying Epcot, I don't think there is any way you can get it all done in that short amount of time. We have taken my DD at both 2 yrs 10 months (last December) and 3 yrs (this May) and Epcot was her absolute favorite park other than MK. Her 1st trip, we were there from the time they opened until the time they closed and did not feel like we had enough time. The second trip we allocated 2 days to Epcot.
DD loved Akershus. Also, the World showcase has lots of Princesses outside in the afternoons with fairly short lines (sometimes even Genie, Aladdin, Dopey and the Beast are out there with the Princesses). If your kids are anything like my DD, she didn't care if she had just seen the same princess in Akershus, she wanted to get in line and see her again outside. Epcot was more about DD wandering around and enjoying herself than running from ride to ride. She loved all the rides you mentioned. What you might not realize is that some of those rides also have areas after them for the kids to explore. For example, there is a whole aquarium area after the Nemo ride.
She loved exploring the WS countries and the KidCot stations and stopping to watch the street performers. On the Future World side, in addition to the rides you mentioned, she also loved Journey into Imagination and the area after that. At 3, she really liked Spaceship earth. Both trips she absolutely loved the boat ride in Mexico and would have ridden it over and over if we let her. The only film we did with her in world showcase was the China one as I wasn't sure how she would do with that, but she absolutely loved seeing it all around her. If you get there just in time for the Princess lunch, you probably won't get finished until sometime between 2:30 and 3:30 which really doesn't leave you much park time. To give you an idea of the walking, I have read that walking from one end of World Showcase to the other end is 1.2 miles.