horizontal side box smoker

Not new to smoking meat but new to side box smokers. Just bought a Char Griller smoker and have a few reservations about being able to control temps and smoke. I have seen all of the articles about the mods for the smoke stack and sealing the  top, but is that really necessary. I have always used a vertical smoker with great success but wanted more cooking space so I bought this. Hope I made a good choice. I am in Mesa Arizona and the weather is great for outdoor cooking and I look forward to learning more about this kind of smoker. Thanks for listening and any comments/tips will be greatly appreciated.