The link below is to an article on rules of the road. The only comment I’d make to all of this is – regarding the tapping on the helmet. The variation I’ve seen in Canada is, if you see a rider point to the sky and circle their hand ( much like the motion of the lights on a cop car ‘cherry version’ ) they are signaling a police presence ahead of you.
I will let you read:
Rules of the Road
Feel free to let me know your thoughts.