didn't know how to start a poll. mods can delete this if you want, thanks

I don't think I do. I believe I look slightly in that direction and on occasion nod slightly, but that I believe is it. For sure I don't say anything. I just keep a very straight course.

That just means snot and loogies should go to the right. 99% of the time.

Yep. I figure the person behind me is going one way or another for a reason, maybe because I'm over one way or the other. So I go ahead and move over and give a little wave. Life is too short to get all snotty about someone going on the "wrong side". The "right side" is whatever works for right then and there.

I do acknowledge a "on your left" and after they pass, I may try to give chase, depending on how fast they're moving.
Some people may just hear "left" and tend to move to the left, causing dangerous situations.

Three fingers of left hand elevated approximately 4 cm off the bar.

yes.

No.

by beginning an all out sprint.

I never get passed so the situation has never come up.

nope

Yes.