1. Ford makes about 5 different GVWR/RAWR packages from a small 6800 gvwr on up to the top at 7850 GVWR and several rar packages. Rawr carries the load. What is your trucks GVWR/RAWR. You really need to weigh the truck front and rear axles separately and use measurement numbers to fine tune the combo.
2. Brake adjustment varies with the combo and brake controller type...wet vs dry pavement....snow on the pavement. I adjust mine for the road conditions.
3. Again angle depends on the truck/trailer combo. There is no generic answer. Like the rest of us you will have to watch and decide for yourself how much angle can be used.
4. I'm guessing you have P tires. When towing a 10k car hauler with the wifes 1500 chevy I air the rears to the max sidewall pressures which is 44 psi. The front changes little if any so I leave them at 38 psi which seems to works best. When not towing I found 32 psi works best for her trucks size and axle load.
Once we find your truclks gvwr/rawr specs and the trailers actual weight I'm sure someone may have the same combo and give more input.