not sure what the prob is with the leak, but in ref to the valve installed upside down, there is no easy fix to correct it. One solution, though I feel you should not have to do it if you hired a licensed plumber, would be to put a diverter on the nipple before the shower head and have the extra opening capped off. I'm not sure how the pressure s going to work with the tub spout since the opening to the showerhead is often reduced in the valve body, thus increasing pressure via restriction.