There is a book for the Hidden Mickeys and then I’m sure a search on the ‘net will pull up more. Basically, there are various forms of Mickey silhouettes - most commonly the ears °O° - subtly placed somewhere in the ride attractions, in the queues, on the walkways, and so on. If this is her first trip, know that the ride ones can be difficult to spot and can take away from the ride experience. (You are so busy looking for Mickey in a particular scene or location that you don’t look at everything else!) BUT, if you re-ride, then it could be fun!
At MK, there is The Muppets Present Great Moments in History in Liberty Square - a really cute show and they have, I think, 4 different stories? Plus, there are so many other entertainers and little performances in all of the parks. I think one day, if I ever go solo to WDW, I would take the time to see all the entertainment that we always seem to pass by going to the next attraction! Anyhow...
Epcot has the KidCot stations in all the countries where she can interact with a CM from that country. AK has the Wilderness Explorers, where you collect “badges” from different stations in the park. At the stations the CMs share information about animals, conservation, etc. Plus oftentimes there are CMs located at animal enclosures just waiting for someone to ask them questions! DHS has lots of shows, so she should be good there.