Thank you again for your detailed and helpful replies.
For calculation purposes you can just assume a digital output pin set to HIGH will have the same voltage as the Vcc value powering the chip, so +5vdc for a 5 volt board and +3.3 volts for a 3.3 volt board.
Is an Arduino Uno a 5 volt board or a 3.3 volt board?
Would all of this work the same if I go through an analog port instead of a digital port?