Is there a breakdown (legend) for "Particle RGB behavior" for the on-board LEDs?
I need 3x analog reads on the prototype card. Am I reading correctly that I need to use A4, A5, A6, or A7 with 3.3 VDC max? If so, what is the ADC resolution?
The Monitor One isn't normally powered off, but you can do so by enabling shipping mode which is how it's shipped from the factory. To turn it back on you need to plug into an external power source. In normal operation you'd use sleep modes instead of turning it off.
There aren't 3 available ADC Inputs on the I/O card. Using the prototype card, you can use available MCU ADCs, which are 0 - 3.3V only, single-ended 12-bit. Note that there is minimal protection on the ADC pins, so you may want to add additional input protection such as rail-to-rail TVS diodes.
OK, one more dumb question. How do you get the cmd box. I was able to find documentation on the funcKey but that did not react to the command on your link.
If you go to the Particle console, select Products, then the product containing your Monitor One. Click the devices icon within your product, then open the device. There's a cmd box there.
The device needs to be online (not connecting to cellular or sleeping) in order to respond to a shipping command OTA.
If you've replaced the Monitor Edge firmware with your own firmware that was not based on Monitor Edge you'll lose functionality including the command box.
It's highly recommended that you start with Tracker Edge or Monitor Edge for Tracker One and Monitor One instead of starting from empty firmware as you would do with other devices.