to answer your questions:
1) Our power meters don't measure left-right balance by using a reed contact to distinguish between 0 to 180 and 180 to 360 degrees, but goes from torque peak to torque peak: it compares the relative power of the left leg power phase with the right leg power phase. So it can be a bit different from Quarq because of the different approach.
2) The calibration figure has no significance. Any offset changes during the ride (between auto zeros) are compensated by the temperature compensation mechanism.
3) Nope, nothing, except make sure you installed the chain rings properly :-)
4) No, we have tested oval rings and they don't inflate power - we measure at 50HZ and don't use discrete, event based cadence.
official power meter of Movistar Team