Hi @flyingfalcon,
I try to give some answers:
It’s not the air speed what the the sensor detects. Its a differential pressure sensor. it senses a pressure difference. There is a relation between the air speed and the sensed differential pressure.
I have written down the basic functionality earlier.
The full process of relating a pressure difference to an airspeed will be more complicated by the fact of changing air density by air pressure (weather and altitude) and air temperature. air density.
Next to these details the pressure difference seen by the sensor/probe will be affected by the presence of the plane itself. indicated airspeed.
Theoretically not, but the plane should be able to fly (at a minimum airspeed) and real world sensors have minimum resolution which makes a minimum airspeed mandatory.
You are right, unfortunately we have to cope with a real world.
As mentioned by others the main purpose of the preflight calibration is the removal of any zero offset by the sensor.
The BARO_GND_TEMP also can help. As shown in the formulas in the links above the air temperature is one of the parameters which affects the air density which als will affect the pressure difference seen by the “air speed sensor”.
Hope this helps.