why is the carousel running forward, and when will it start running backwards and why?

The carousel indicates that Dark and Cooger have the power to actually turn back the aging process. Of course, this chapter also begs the question of what happens when the carousel runs forward. The "Funeral March" is a symbolic choice of music for the carousel. As the carousel spins backwards and the music plays in reverse, it is as if Mr. Cooger was marching away from the grave, instead of towards it.