> "Most stop signs just mean slow down."

Which must be why "stop means STOP!!!" was repeated very forcefully by the driving instructor and the friendly police officer multiple times during my driving course.

In what country or state? In California they definitely mean you must make a full stop. Also people seem to have forgotten any of the rules of priority at stop lights. (Straight and right always come before left. Right on red is below everything else.)

No, that's a yield sign.