I'm an intern at an architecture firm in Minneapolis, MN and have run across your post here in my search for some of the same answers. I've found a couple of websites that might help you out. http://www.obdyke.com is the manufacturer of cedar breather and they also now make a product called Home Slicker that is designed as a rainscreen for vertical applications, also check out this article http://www.buildingscience.com/resources/walls/siding_rainscreen_question.htm They have specific information on what to do for the back priming / sealing of boards, and yes it is recommended, but you have to watch if you use oil based primers or another type of water repellant based on the situation. Hope this helps you out a bit.
My personal inclination would to use the Home Slicker / cedar breather like product because it is continuous support under your board. That way you won't get balooning that sometimes occurs wi with the furring strips, plus it does cut down on your wall thickness and trim details are easier to do. Thats just based on my research from today tho, and I'm by no means an expert.