Focal is obvious - it is the same thing as the focal of a real camera. I use value from 28 (wide angle) to 80 (telephoto)
focus distance and f-stop are related to Depth of Field : focus distance correspond to the focal position and f-stop is your camera aperture (The larger the number, the smaller the aperture opening, the lesser depth of field effect)
shutter open/close is related to your camera speed and is only used if you make an animation with motion blur activated
Hitter and yon control the cliping plane position for the preview : hither is the minimum distance where the object are seen in the camera windows there as yon is the maximum distance. None of them have an impact on render.