I dont about all those current draw scenarios but what you mentioned aboout the voltage regulator, I just did over the weekend. Its inside the cap and can be replaced separately yourself. Its about 40 bucks, but test, test , test as everyone says.In this case, put a voltmeter on the battery when running idle the first 30 seconds when you cranked the engine. The readings should be between 13.5- 14.8. Anything less than 13 volts means your battery is not being charged or was drained like a vacuum germ.
Anyway you got a lot of feedback, now you do some of the above, come back and tell us what it was so we can all benefit..thats the premise of brickboard. You got to give just as much as you take advice.
good luck!