It depends on your riding style, but for a Loaded board, I'd suggest something like Paris brand longboard trucks or Randal brand longboard trucks.
Absolutely not, it is all preference. Some people have loose trucks or tight trucks; also experiment with bushings, they will affect the ride greatly.
My personal favorite longboard trucks are Paris trucks.
Longboard trucks can be bought from any stockist of skateboarding equipment or from online retailers such as Amazon. They cost around forty dollars for a pair.
The answer to your question is in the questiong itself.
yeah, you can get them from Tensor
loose trucks and a wide board
Buy wheels, trucks, and a deck and screw them together
yeah, you'll need risers
kingpins usually face outward on longboards
Yes, just swap your bearings from skate wheels to longboard wheels, its all the same.
The shape of a longboard was invented before but the trucks and wheels were small like those of a skateboard. Early boards didn't have pop.