My understanding is that higher pressures are better on wet roads (to squeegee out the water and prevent hydroplaning) however lower pressures are better on dry, gravel, or sand (more surface area). I think manufacturers used to specify lower pressures because they gave a more comfortable ride, but with the push for greater gas mileage and the scandal with the Firestone tires on Ford Explorers (the specified pressure was way too low) I'd doubt that they would still do this.

The difference between switching to neutral (or even manually shutting off the engine) and having it done automatically is one of control. When the TCH shuts the ICE off you still have full braking and steering and power is available instantly (albeit limited to 40HP until the ICE kicks in again). When a conventional car is shut off to coast you loose the power assist in the brakes and steering and restarting for power is more involved. Thus it is potentially dangerous.

The merits of tailgating trucks are so offset by the dangers, it isn't worth discussing. I don't even like to be anywhere near their tails. Have you ever been behind one that has thrown a tire tread? Forget the pebbles!