For your sound issue I just fixed mine. You need to update Rom U36. But if you download the regular version from IPDB it won't work and will have the cracklin' sounds. You need to download the PinMame Version and burn u36 and replace it in your game. That will fix your issue.
I don't have a cliffy on mine but I can see how that would cause a problem. Either adjust the deflector plate, build up a couple layers of mylar in front of the cliffy edge, or take off the cliffy.