Somewhat true but incorrect. Eyes do indeed adapt to light but the rod photoreceptors in your eye that allow you to see without lights become "bleached" upon exposure to just about any white light. The rods contain more photopigment but it is slow to respond after it has been "bleached" (i.e. exposed to light). It takes roughly 30 minutes of continuous dark for the rods to return to the ground state. In other words, they are very sensitive but easily overwhelmed. Astronomers (amateur and professional) use (weak) red lights to illuminate their area at night to avoid bleaching out the rods.

This is just wrong. Once you've turned on a light, your vision outside of that beam of light is shot...see above. A more intense light doesn't have much effect on the cone photoreceptors which are less sensitive and recover more quickly. High beams or low beams on a car won't make much difference. The high beams just illuminate further down the road. Your night vision is already shot.

Nope. Try an experiment. Walk (or ride) across a dark field with a light of some kind at night...any light will do. In the middle of the field, turn off the light and try to walk back. You basically won't be able to see anything for quite a while. Do the same thing but wait 30 minutes before you start back, you'll be able to see a whole lot more. I've often experienced this while camping in dark sky areas. In the middle of a moonless night, with just star light, I can walk around without problem. I might even be able to ride a bike. But if I happen to snap on a light, I can't walk anywhere for a long time.

Bottom line, once you've turned on a light, your "night vision" is "night blindness".