I have been asking similar questions in the forums, and like you, i also want to publish interactive children's book apps for ipad, iphone etc.
There seems to be an issue with such apps because you're using many static background images for the pages with some sprite interaction and text - right?
I am still not decided on the engine or SDK yet! I have seen some amazing book apps on the itunes store created with Corona SDK, Cocos2D, AIR with Starling etc. You certainly don't want your app crashing as it will lead to bad reviews and kill your credibility, no matter how great the story and illustrations are.
Sorry i don't have an answer, but i'd like to hear how you got on and if you could offer me some mistakes to avoid.
Good luck with your book!
PS Here is a children's interactive book demo on youtube created with cocos2D and weighing in at 105mb. http://www.youtube.com/watch?v=aL--x8DFPQ0&list=FL8o9fMRsueGao8LsRl2znXA&index=6