Hi Doug,
In triggered exposure mode, the frame rate display does not show the actual frame rate, only the maximum you can run it at. You can't run triggered exposure faster than the camera is set to, it will drop frames.
The exposure control will control the shutter speed, provided you are triggering the camera at or below the frame rate it's set to. If you for example set the camera to 30fps and provide a 1000Hz trigger signal, undefined operation may occur. Let me know if you still have the problem with the shutter control when operating within limits.
Sound is not supported yet.
David