Welcome to the forum Dick and congrats on your purchase of a new PC. There are many more savy individuals on this forum that I am sure will chime in to answers your questions better than I will but I will try my best...the sinks, shower all empty into the gray water tank, the toilet is the only waste that goes into the black water tank. What is nice on my 2551 and I am sure on the 2910 is that I can open both gate valves and mix the two tanks and get more total capacity. There is a 12V plug on your TV ant. boost plug and that comes off of the coach battery, should be in one of you front over head cabnets. The slide, and stair are wired off the chassis battery all other detectors come off the coach battery. The stair switch has and on/off setting, the off leaves it in the out position all the time and it only retracts when the ignition is turned on, in the other setting the stair goes in and out everytime the door is opened or closed and a yellow light will stay on under the stair. I have no idea what the" significant" draw would be from unless there is short circut somewhere. The main battery shut off is right at the doorway and all other fuses, breakers, etc are near the fuse panel and the inverter/converter, not sure where that allmight be located in the 2910. bets of luck