Don't give up, chicken over a charcoal fire is delicious. It takes some time to figure out each meat/wood/rub/sauce combination works for you.
I think the pan (casserole) was not a great idea, you can make great chicken in a pan of course, but, it will be best on the rack. This allows for more smoke and not sitting in the juices.
I like to brine chickens, but, I will often cook them longer if I have brined, the skin renders better and the slightly over-done meat will still have a great texture. Wampus is right, though, if you brine, let the chicken air cure for a bit.
I cook chickens closer to 400F and I don't understand why you would shut down the vents for chicken. Let it run until it's done. Not like ribs, chicken is not like ribs, important to know that.
me: I don't drink anymore
Yelonutz: me either, but, then again, I don't drink any less