Question: what are good questions to ask an author about their book?
Answer: What inspired you to write this book? ... 
Can you tell me about the book? ... 
What did you learn when writing the book?
What surprised you the most?
What does the title mean? ... 
What did the subject(s) of the book think of it? ... 
What are the subject(s) doing now? ... 
Did the book make you like the subject(s) more or less?