Put some weight in the bed. Enough to make the springs start working. This will soften the harsh bouncing.
Gearing down and anticipating stops is the key.
It doesn't get up to speed in a hurry and it won't stop in a hurry.
The suspension is quite robust and can take the abuse of road driving at normal speeds.
Front shocks should help with the shimmy.
Tire truing will also help with smoothing out the ride.
Do you know if the king pins are in good shape? Worn king pins will contribute to the shimmy and wobble.
