A few things:
I use a Maverick ET-732 remote thermometer, around $60; a slightly older model than the 733. It still works like a champ and I highly recommend it for overnight cooks. You can monitor meat temp and smoker temp from the comfort of your warm bed, instead of babysitting the smoker all night.
Cooking time is only an estimate. Every piece of meat is different, and cooks differently. I've had an 8 lb. pork butt take only 6 hours, and I've had one go 16, with identical smoking techniques. The ones I did Sunday never did an actual stall, but moved steadily but slowly upward. Even so, I still foiled at 165° IT, and I also save the juices to pour back onto the meat after pulling. The gravy separator is a must, as about 1/3 of it is fat. Then comes a vinegar-based finishing sauce for an extra layer of flavor.
The water bowl serves 2 purposes. It keeps the smoker environment moist on long smokes for lean cuts of meat like brisket (not necessary for fatty things like pork butt), and it acts as a heat sink to help regulate and steady the temp inside the smoker. When smoking something that doesn't need extra moisture, I fill mine with playground sand and foil the top. That way I still get the benefit of the heat sink feature.