i have a 2008 F250 diesel Super Duty. I am getting into the hauling business. How much can this truck handle in regard to weight capacity? Am I better off hauling a 3 car trailer or a flatbed trailer hauling freight ?

If your truck is a 6.4 do not use it to haul anything beyond personal items. The 6.4 isnt reliable enough to start a business with and expect to stay afloat.

i have been using the 6.4 f250 for work already for sometime towing RV trailers and Campers to dealerships for 8 months now . Towing 10k-13k campers

The 6.0 is worse! Depending on how your truck is equipped it could tow 15,000 pounds or so. As far as what type of trailer it all depends on what you are hauling. I would be beefing up the transmission, engine and rear axle cooling if I were hauling all the time.

One of the worst problems with the 6.4 is the regeneration cycle that dumps a lot of fuel into the oil. There are fixes that you can find for this issue.

Read this -- http://www.trucktrend.com/cool-trucks/1212dp-6-4l-problems/