I agree with adamclyde. Fill the charcoal ring with unlit coals, having tucked in a few pieces of smokewood so you'll get some smoke throughout your cook, and definitely with one piece on top where you are going to dump your chimney of 8 or 10 lit coals (you don't need many more lit coals than that except maybe in the dead of winter).
Start with your vents wide open (the top vent ALWAYS---you won't mess with that one)--so all three at the bottom should be open. Then you monitor the temps as they quickly start to climb over the next half hour or so, and when it's on its way to your desired pit temp (say 225 if you're doing pork butts) you start closing the bottom 3 vents somewhat. Maybe halfway. Maybe 2/3 of the way. Maybe you close 2 of them entirely and then only use 1 vent to control the whole cook (some of us prefer that---easier to manage!).
If you are keeping your temps low, your fuel should definitely last thru the night. If you are using the Brinkmann charcoal pan as your water pan (twice as big as the one that comes with the WSM) then your water will last, too. If not, there's still a chance your water will last, if you really keep your cook low and slow. But you might need to add some, so have a long necked something standing by. Watering can, wine bottle, or I use a dedicated gas can that has been painted blue so I don't grab the wrong one in the middle of the night and run into trouble...!
