The worst case is when they expect to turn right soon; I consistently have drivers half-overtake me and then start moving towards me, or turn right across a bike lane without looking.
When I took my driving test in Ireland the examiner marked me down for checking for cyclists and simply said "there won't be any cyclists doing 20kph" - which of course is a very normal cycling speed.
I don't think I've ever forgotten about a biker I've passed, but I also like to avoid situations where I might forget, which put the biker in a position to surprise me, or which impede my maneuverability if something else happens.
But while I'm okay poking along for a block, if there's traffic behind me then that could result in an impatient driver overtaking both of us, which could be far worse. It's a tricky balancing act.
I will admit to having a mildly "political" motive, in that I would like drivers to have a positive experience dealing with cyclists. So I'm probably more courteous than the bare minimum required by the traffic laws. I get out of the way if I'm backing up traffic, whether driving a car or riding my bike.
My general preference is to find routes where there's minimal car traffic.
Me too, except the other way around. I will make sure there is a ton of room before merging in front of a bicyclist, and I will give them the full lane on a two lane road when passing them even if they're hugging the curb.
When riding on the streets, they are given the same legal protection as any other vehicle. I just wish that every bicyclist also knew that they have to follow every law a car does too - including stopping at red lights and stop signs.
Either way, it sounds like you've given it a lot of thought so you're likely the least of my worries. Just imagine it would be your child on the bicycle and you'll probably do the right thing. (Short of picking them up -- don't do that.)