Everything you said is true. I had to make many last-minute changes to the Game, including on the Z layering which made it less consistent, though It was never truly "Working" Before. I'll try a shadow shader instead. An actual feeling of depth is really important in a game like this.
I think maybe removing the Slerp function on the movement vector is causing the Slippry-ness you're talking about. I'll try removing it.
Thanks for the feedback