Should I stop at intersections where I have right of way and a driver on the cross street might be turning right on red? (I can't tell precisely because far too many people don't signal.) Because that's the most frequent reason I'll give a few toots of the horn.

Definitely not if you have the right of way. I do the same thing when I'm driving and I see a car creeping forward to making a right turn as I approach the intersection.