Update:

Wheel cylinder finally effing replaced with a new line that I found at autozone that was exactly the light length!

The autozone spring kit is... Weird. The tension clips that hold the shoes in place are way, way too strong. I reused the OEM clips.

I just tested everything. Everything works as it should. I'll be able to get home tonight and to work tomorrow.

The wheel bearings certainly need to be replaced. They aren't loose, but spinning the hub by hand, they are stiff. The grease is likely solidified after 375k miles. It's time to change them. Thankfully, a fiend has a lift and a big air compressor. I'll be ordering parts and will get pretty much everything else in the rear changed out.

I'm relieved but also really annoyed and more than a little worn out.