Marco, thank you! That was the hint I needed to move on.
tl;dr: I got it working, and sound is playing!
Long version:
I deleted the journal files with:
rm -rf /var/log/journal/*
Thanks to sgk.ssci in this thread: write error: No space left on device
And configured the journal for 200K in /etc/systemd/journald.conf
as outlined in this troubleshooting doc: Troubleshooting Intel® Edison and Intel® Galileo | Intel® Developer Zone
I Did a reboot, and was able to edit the base-feeds files, install kernel-module-snd-usb-audio.
lsmod did not initially show the hardware, I switched to an brick power supply, and the sound card's LED lit up.
From there, lsmod showed the snd_ modules!
After that, I think it was just alsa.. and then was able to play the sample .wav file.
Thanks again, Ruscoff ! Also thanks: mweal for your input, and AlexT_Intel for so much too.