Yeah, that would be wise, it's the only fool-proof way to ensure the sensors are properly configured.
This is expected behaviour. It would be like trying to measure the length of a horse that is running away from you.
No, because that also configures the divisor, which is used internally.
Yes, by switching off your NXT or smashing the light with a hammer. I would not recommend the latter and the former will make it more difficult to use the sensor and NXT.
I don't know, tbh

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