Is there a GUI settings manager for Mutter? Something where I can adjust the window shadow size, or the hot corners, or opacity, etc...
Mutter is lean and mean by design, and is for sure way less configurable than Compiz. That's a choice made by the GNOME designers, who place simplicity and maintainability above configurability.
Also, this Fedora Gnome 3 Tips page has a few interesting paths to explore in gconf, and you might find a few interesting not exactly mutter-related but still interesting in