Dave - I know you're no BBQ rookie, but 2 things kind of jump out at me on your plan. First, you're brining before the bird is thawed. You want to make sure it is completely thawed before smoking it! Also, the size is pushing the limit of safety. 12-13 lbs is ideal, but up to 14 is even pushing it a bit. The problem is the time the bird stays between 40° and 140°. If the bird is too big, you risk growing some added "side items" you didn't plan on. I think a 15 pounder will be alright, if you smoke at 250°, but I recommend trying to keep your turkeys 14 # and under.
One recommendation on the thaw - keep it in the bag, and thaw in cold water in the sink, changing the water every 30-min. You can finish thawing one pretty quick, and that way it's completely thawed before taking a swim in the brine.