Glad to hear the PDF solved some of your questions.
Regarding the size of the increments, it should be large enough, such that the output signal can be clearly distinguishable from noise.
In other words, the size of the increments should be large enough such that the output signal displays a clear curve that the pidtuner tool can identify, but not too large so you avoid damaging your hardware.
As a rule of thumb, I always try to split my operating range in 3 to 5 levels.