Update on the alternator. I was inspired to take the car out for a drive, so I charged the battery, took it out on the interstate, ran it up to 90 or so, turned around at the next interchange, came back, and on the way back glanced at the voltmeter, and Glory Be! It was charging! I have driven the care several times since, it always charges normally. So, I don't know if it was taking things off and putting things on again that knocked loose some corrosion, or what, but I aure am glad that it is working.
So, at least for now, no need for a new alternator.