smokednalberta: I bought one of those this Fall. I used a Brinkman Smok'n'Grill for nearly thirty years. All I use for wood is thumb-sized stick of green White Poplar. I cut them about 4-5 inches long and keep some in a coffee can in the freezer, so I always have a supply!
I put a cut-up onion, whatever old BBQ sauce I want rid of, maybe some other spices, maybe not, in the water bowl and keep it at a temp where the water just barely rolls. I start with a couple of the green sticks and maybe add another one or two, depending on what I am cooking. I usually smear some BBQ sauce on the meat as well, but not until half done or so. We cooked corn, chicken, turkey, deer, beef, pork, sausage, pork baby back ribs (oh man, those ribs!), beef ribs in our old Brinkman. Any left over meat gets cut up in little cubes and into the soup. One time we cooked a beef roast and used the drippings as the base for soup. That was excellent!! This Fall, I cooked a nice little beef roast, and cut up the left over and put cubes into WeightWatchers* Smart Ones Southwestern Vegetable soup. That, too, was excellent. I am not into "weight watching", but the stuff looked like a good base for "smoked" beef roast leftovers.
Enjoy your Grill Pro. I like mine.