So....my conclusion is that if you are in flight and the BAT DISCHARGE light illuminates all on it's lonesome, it is not going to have a detrimental effect on the flight. I would appreciate your opinion on that conclusion
Thats right,and the checklist says to continue on your way..
The APU if needed can be started as long as xfer bus 1 is powered and if not, by using DC from the battery if its voltage is sufficient (i think 20 dc in air and 18 on ground).
Your A and B are correct.
Never had a this problem so far so no first hand experience here.