Maybe a strange or obvious questions about your books:

1) When the overs change from one edition to the next, what is the reason/who initiates it? And do you have any say and/or final say in how the covers appear?

2) Is there any chance that your books would ever be packaged into sets (based on theme) for purchase instead of individually? Or does that require a certain volume of sales, or would it otherwise hurt your existing sales?