+1 on the digital scale! You will be surprised how little wood is needed to get 3oz. For ribs, you could go a little higher to say 4oz, but 3 oz will get the job done as well. I would also recommend getting a remote thermometer (like the Maverick on the SI web site), but you won't need a therm for the ribs. Just put them in bone side down, and no peeky for 5 hours. After 5hrs, check to see if the meat is pulling back from the bone; if not, let them go another 30 mins or so.
To sauce ribs, I remove them from the smoker at 4.5 hours, sauce them up, and let them go for another hour to finish. Let's us know how you make out!