Air bags are a good idea for towing. I wouldn't use them for any lift though. Your ride quality will suffer. Look into "X" code springs for the front. They were an option on trucks with the snow plow package. They should gain you 2-3 inches and are better than a spring pack leveling kit. Find...
Look into a transmission cooler from the 6.0 liter powerstrokes. A good tune can actually help with longevity. PHP, gearhead, etc. You generally want to double your weight with your winch. For example, if your truck weighs 5,000 go with a 10,000 lb winch. The Warn hubs are a good upgrade. Most...