In the first place you should already be on low beams by the time you overtake because the high beams shining in the mirror are very uncomfortable and blinding for the car you are passing. This would be seen as common consideration for the comfort and safety of a fellow driver. If you can see a car at night either driving in the same direction in front of you or oncoming you should be using low beams in order to prevent blinding people.
Because - as you overtake the vehicle in front, high-beams will be reflected straight back at the driver - through their mirrors. Low beams are angled more towards the ground.
You should use your low beams to avoid blinding the driver ahead as you lights reflect in his mirrors.
Both.
Yes, that would be common sense.
500 meters
Look to the side of the road and at the white line.
Use low beams.
You must dim your high-beams if you're within 500 feet of an approaching car and dim your high-beams within 300 feet of the vehicle you follow.
500 feet
Turn Signals, Low Beams, High Beams and Flashers
The right side
You need to turn your high beams down and ,after the car passes, you may turn them back to high beams