Update - looks like things improved with the shifting overnight. When the bf rode it in the am, it was working a lot better. Maybe we have bike mechanic gnomes in the garage or something.

It was still crazy squeaky (I forgot to mention that it was squeaky too), so he dropped by the bike shop on his way to work. They had to take a bunch of stuff apart, but they got rid of the squeaks. All seems well.

So, yay, everything is working now. Boo, we sure had to go through a lot to get to this point.