To be nice!!
The word "courtesy" means polite behavior that shows respect for other people. Thus you would use a courtesy title when you were meeting people formally or introducing them to others.
fuel economy, very effective during highway driving,
Courtesy is a very important thing to know.
You should use low beams when driving in fog. It is more difficult to see driving with high beams in fog.
Yes. This the main reason why there are cell phone use laws while driving.
Congressional Courtesy is the rule that congressmen use to ignore people not in their state or district.
Yes.
No, just use one space.
Yes.
No, you should not.
Your headlights should be set to low-beams whenever you meet oncoming traffic, as a courtesy to prevent your headlights from distracting the other driver. You should also use low beams when driving in fog or heavy rain, to prevent light reflected by the rain or fog from blinding YOU.