Yes, it's all correctly explained there, so better read it straight from there.

About the DC/AC/modulation/bias/waveform thing, I'm not even going to start.
It's the Hall-effect sensor that is switch-like in operation whereas the variable Reluctor (VR) sensor, as used together with EDIS, gives out a voltage that is proportional to the rate of change of magnetic flux density at the sensor tip. Yes, the sensor has an inbuilt permanent magnet and therefore reacts to the presence of iron. The crank sensor tip can collect iron debris and lead to malfunction. The EDIS is not firing at 90 BTDC but it's triggering with the missing tooth at that position. The unit will "fire" the coil at an angle specified by the ECU with SAW signal pulse width, usually within 45-10 BTDC, rarely at TDC. In the absence of a valid SAW signal the unit will default to 10degrees BTDC that will get the car home with limited power and terrible mileage.

Toe Knee, if you're not sure whether you have the correct sensor/holder combination, you better measure the air gap between the sensor tip and the flywheel teeth. It should not be more than 2-3 mm to give adequately high signal amplitude for EDIS. If it all works, you should see the revs rise in the tacho while you crank. The 10V while cranking is somewhat normal and the ECU/EDIS should work fine with much lower voltages than that.