Dus jij wilt tovenaar worden

The magic feels so unique and well-thought-out, but I wonder what inspired the specific rules and limitations Diane Duane chose.

The protagonist's journey felt really relatable, especially the moments of doubt and empowerment. Was that intentional to inspire young readers?

I noticed some clues that suggest there might be more to explore in this universe. Did others pick up on any foreshadowing for later books?