While researching for whether anyone else had found a solution for my audio issues, I discovered that mame4all doesn't support screen rotation.  Bogus!

So now I'm going to try to use lr-mame2000 (the same version the MAME core code, but built on top of the Libretro platform) on the current release of RetroPie (4.7.1) - hopefully I won't have as many issues (or it won't be such a headache to resolve them).