When the cell is yellow, it means, you have already SCed at least 50 cubes, which means, that you’re qualified to get the first tier bonus, and the green ones means, that you’re at least at 100 cubes, so you’ll get the second tier bonus. So the colors are to tell you, if you have already enough cubes SCed in each cell, to qualify for a bonus. With the colors you can easily say on which cells you should work to get the bonus and which are already good for you, without looking at the numbers.
And yes, the values are based on what each user has done so far, so it specifically shows the number of your SC votes and the number of cubes still available for you (it’s different for different players).
Not sure about the categories, I will have to think about it.
The 24h column is useful to see, if there was some activity in a given cell recently or maybe the cell need some working on it.
The columns’ names shortening wouldn’t help much, because there still have to be some space between the numbers. Otherwise, everything would become totally unreadable. Maybe only the “Eyewirers” one could be a little narrower.