1) You can get all the parts needed at Home Depot. They make a surface-mount wire raceway that could run up the wall and over to the existing light. You leave the switch on the light in the on position, and the lower switch will interrupt power to turn it off/on.
http://www.homedepot.com/p/Legrand-Wiremold-Cordmate-II-Kit-C210/100657473
http://www.amazon.com/Leviton-42777-1WB-Surface-Backbox-Single/dp/B00332F4I0/ref=sr_1_2?ie=UTF8&qid=1394164489&sr=8-2&keywords=surface+mount+electrical+box
2) Easy enough to do with 12volts. You could use the same wire raceway mentioned above... I would see if you could tuck the wiring behind the wall panels.