So unless there is another higher-resolution camera (or a higher resolution mode) aboard this craft, we really cannot expect to see much fine detail as Ceres is approached. At 480m/pixel, the smallest object we could see is 480 meters in size? Or is my understanding of this faulty?
No, because the camera will be closer the parallax will allow each pixel to encompass fewer pixels. If the camera were sitting on Ceres, then you'd see millimeters per pixel, because the camera would be that close. . . if it could macro focus (unlikely). My Aunt worked for NSA before her retirement in the 1980s and they had military satellites then that could, she said, read the license plate numbers in the Kremlin's parking lot from 117 mile orbits. . . If atmospheric conditions were just right, which was very rare. Those cameras then were analogue and had far less resolution than do these cameras on Dawn. When Dawn gets close enough, we will see a lot more detail. We just have to wait.