The issue with the M-8 coming to a stop is correct. This happens with all the vehicles. I think what it represents is the hull hitting the ground and bringing the vehicle to a stop. Kind of like hitting a steep dirt bank. And yes, I know the hull is designed so that this wouldn't happen at the angle your talking about, but in this model it does. Same thing with the Panzers, M-3s etc. In AH1 you would normally just roll, bounce or what ever and die. Not any more.
Hope answers your question.
As for the sound issue, I haven't encountered it. Good luck.
LTARsqrl