Hi,
To try and answer your questions:
1) No idea why the latest release doesn't save the volume on shutdown, however to get a non-zero volume before booting, I sent the "+" command from my keyboard when connected over serial to raise the volume up by a single notch. After the command is sent it should tell you the new volume I believe. I kept resending "+" until I got the volume to around 20ish (max 24), and then I pressed "s" to write the config. Now when I boot my system the volume is always set to 20 by default.
2) Unfortunately I am just ignoring these console warnings, I get them also. I did read this, not sure if it is related: https://github.com/RetroPie/RetroPie-Setup/issues/1077
It is safe to ignore the warnings, even though it is annoying. I have no idea how to solve this.
Cheers
