whats max.towing weight for a trailer,,,and the payload weight

This is your owners manual, follow the manufacture's guide lines. You dont want to overload your truck!

Ford lists your Gross Vehicle Weight Rating (GVWR), your Gross Combined Weight Rating (GCWR) and Gross Vehicle Weight (GVW) on a label on the drivers door jam. This will tell you what the maximum vehicle weight can be, and you can back into your maximum towing weight that way.

That will depend on your trailer hitch and tongue of your trailer. I have had 3-4 tons on a 16 foot trailer, but it made my truck sit down in the back. I bought a set of super springs to add to my leaf springs and that corrected it. Super springs cost about $450, but worth it if you pull a trailer most of time.