Thanks again for the lengthy explaination @Back East Don. I read through your info. twice - will probably need to read again to fully understand it but at least now I know how to tell if the electronic is 12v, look at the back and the Output. I've always looked back there but it's been jargon to me until now.
And you used the lamp 2 conductor cable from the home depot to extend the 12v wiring so you could plug in your fan at multiple locations - using the ribbed part as the ground. That's cool - pun intended - and it seems pretty easy to do - except for the part about the DC section of your power center. Do you mean the box under (my) sofa with all the fuses? If so, do you just connect the cable to an unused fuse terminal? Is that how you add an extra 12v power outlet?
Thanks for the pictures, they are very helpful.