How should I level the concrete foundations for my fence's CMU block pillars?
First off, your last question, which is most answerable:


  how to you level discontiguous pads of concrete 10 feet away from one another?


Homeowner, these days, a laser level is easiest unless you happen to accumulate old survey equipment (guilty.) But you use the same techniques that work with a dumpy level or a transit - shoot a level line, and measure how far below it your surface is. Two things that are 42" below a level line are at the same level. If one is 44" below, it's 2 inches lower. 41-3/8" it's 5/8" higher. With CMU, adjust to the nearest 8 inches if using mortar, or the actual height of a block (no mortar) if using blockbond. Nails on the inside of the form is the usual level mark before pouring concrete in.

Whether you set the fence "level" or follow the grade is, well, up to you, people do it both ways, matter of opinion, also tends to vary in a practical sense with how far out the grade is (a level fence might be 4 feet high at one end and 20 at the other, which gets a little impractical and suggests following the slope more.)

You can use the level and measuring stick to determine exactly how far off level your grade actually is, if that would help you come to a conclusion.