Typically WYSIWYG (what you see is what you get) - however, even though the old Nikon film SLR camera lenses will fit on a Nikon DSLR camera mount, what you see through the SLR viewfinder is NOT what you get in your shot. The DSLR camera will capture about 66% of the picture that you see in the viewfinder IF you use the old film camera lenses. Also, the focal length of the old film camera lens will be nearly doubled. The cost of the sensors in digital cameras rises exponentially with respect to increased size. This link will provide a detailed explanation: http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm
However, if you purchase a lens designed for digital Nikons, the image that you see through the viewfinder is what you will capture in the shot.
Now for sports shots. Focal lengths from 80 to 200 will work fine, but keep in mind that for a 200mm shot, the camera must preferably be tripod mounted. A slow shutter speed (depending on the sports) of 1/60 to 1/125 will usually provide some motion in the sports activity. Some test shots and experimentation is highly recommended. A 'frozen' sports scene robs the picture of motion. Also, image stabilization might actually turn out to be a negative; therefore experiment.
Hope this helps.