Watertech responded to my questions...

Adding here in case it may benefit someone else:

There is a swivel on the end of the floating cable (plug end) that will help remove twists and kinks in the cable. How it works:
Hold the swivel in your hand and walk away from the machine in a straight line, the the cable will turn inside the swivel and the cable will straighten out; with the cable completely straight and no slack, give the cable a couple of shakes.

To avoid the cable from tangling in the first place, always switch the direction of the unit's handle (mirror image) every time you use it.
What causes the cable to twist on any robotic machine (this is true for Dolphins, Aquabots, etc.) is the machine running the same pattern every time it's used. Switching the direction of the handle causes the machine to run it's pattern in the opposite direction.

There are two different residential Blue Diamond models, a standard machine and a remote control machine:
The R/C model uses two drive motors and a split wheel tube so the machine can turn one set of wheels one way and the other in the opposite direction to make turns, so this unit has four brushes/rollers.
The standard machine uses only one drive motor and navigates turns using a completely different method; this machine only has two brushes/rollers, on on the front, one on the back.