here is a place to calculate your heating load based on size of your unit and insulation, this is total wattage, you can also break up the elements
http://www.heater-store.com/heater_calculator_info.htmas for controlling the elements i recommend auber inst.
http://www.auberins.com/a few of the items i think you would need is a PID, Relay or Relays depending on how many heating elements you get, also of you run an electric smoke generator maybe a timer to turn it off...
another thought is amazing smoker products, they have trays , and tubs that use pellets or saw dust to produce smoke.
http://www.amazenproducts.com/Default.aspgood luck and have fun with your project,,, would like to see pics of the project
Beef