I enthusiastically second #1 & #2 above.

The very best part of Ende's fiction, in my opinion, is his examination of the difference between belief and knowledge. Bastian believes that all sorts of things are good and desirable, but when he enacts his will, he finds that he does nothing but harm.

The theme of skepticism - especially skepticism about what is good, evil, and necessary - is immensely important, and it's one of the key themes of The Neverending Story.