Thanks, I'm really glad it helped! I did still use the Pixhawk because eventually I was going to use autonomous navigation which is really easy with Pixhawk/Mission Planner.

I powered the motors with two of these in series: www.superdroidrobots.com/shop/item.aspx/interstate-12-volt-8-ah-sealed-lead-acid-battery-sla-0-250-faston/1221/. Never tested it for more than an hour but I never noticed much of a battery level drop. I used these wheels: www.superdroidrobots.com/shop/item.aspx/atr-wheel-and-shaft-set-pair-8mm-bore-10-inch-traction-lug/1995/ I followed this robot closely: www.superdroidrobots.com/shop/item.aspx/new-prebuilt-4wd-ig42-sb-custom-length-and-width-robot/2806/