bcharleson - real busy now - briefly -
All of those functions - Play, Pause, Skip Forward Skip Back, Volume Up/Down/Mute, and more - are already built-in.
The standard-issue keymap has them, accessible from the home row Media chord.
They're actually a layer of the same location and arrangement as the engraved Inverted-T cursor keys.
That makes them inherently very mnemonic, and very easy to reach without looking.
You can jump to them right in the midst of typing, and then jump right back to typing, without ever needing to look or reposition your hands.
If you love music, they're super handy to have.