The bearings do not seem to have any play at all. I really expected the fan to turn more easily after oiling, but this did not happen. And since this is balanced as an assembly, I did not remove the cages. It stops dead as soon as I let go with the cages on.
For the voltage, it appears the regulator uses the control voltage to determine how much of the 12v (red wire) to send to the motor, and grounds the remainder (converts to heat, ergo the pentium-class heatsink). At least this is my current understanding. (no pun intended)