Dave, you're already in the casting business? That you don't know much about the Wiz is kind of strange.
One of my best friends is a casting director. One of the duties of a casting director is to be familiar with, or know well, all shows. You must attend shows every night. And while doing so, you should familiarize yourself with all the actors, old and new, on the scene.
As far as casting goes, my experience is limited to a few free lance gigs with Bernie Telsey. Otherwise, I've been in the business since the 80's, as an actor, and then in theater management. From what you post here, you don't sound like someone who would do well in casting.
<-----I'M TOTES ROLLING MY EYES