What lessons could the Soundkeeper learn from Dischord and Dynne?

Why does Faintly Macabre remain in prison, despite knowing how to escape?

Who might the anonymous sender of the tollbooth be? What reasons would he or she have to send it to Milo?

What would the King of Wisdom—Azaz and the Mathemagician's father—think of the state of things in the Lands Beyond? Would he be pleased with the way his sons have been looking after the kindgom?

What would have happened to Milo if Tock had not shown up in the Doldrums? Would he have stayed there forever?