Any wave you do just makes your other hand numb sooner.
If you can do the sprinkler your steering dampener is turned up to far.
uhh.....on point number 1... No? Shouldn't be putting that much weight on your hands...
Point number 2.... if its a fairly straight road, you should be able to let go of the bars, steer with your knees on the tank enough to stay in your lane, and do the ymca until you've slowed down too much. even if your bike is damperless. if have to constantly be putting in some steering input to keep the bike from turning, then either you are riding on the worlds worst pothole laden rodes, or there's a mechanical problem.
personally, i do the hand below the bar, two finger wave, though often more like the "Wooderson greeting" (see also: opening scene of role models) - meaning fingers together than the peace sign. If I think somebody is ridiculous, i'll do the awkward hand up, rapid arm movement, floppy hand wave. Just to try to embarass them.
and hand patting head for "heads up" be it really slow traffic around a bend, animals, police, children (see animals), etc. The foot-off looks more like stretching to me on the street, there is too few track riders to effectively communicate a 'foot-off'.
