Bill,
I think you'll find that "alsactl store" saves the mixer parameters to a
file (/var/lib/alsa/asound.state) and then you have to read them back in with
"alsactl restore". I don't think it's automatic, so you'd want to
add the command to one of the startup scripts.
Unfortunately I can't help much with your rc.local problem. I'd expect google has
the answer if you can figure out the correct question to ask it. Might be a path problem
- something that wouldn't be an issue from an interactive shell, but no good at boot
time.
Graham