[Suicide Junkie]

It does not take any energy to apply a force.
It does take energy to accelerate an object.

You gain energy if you fall in a gravitational field (since you are moving with the force.
You lose energy if you move against the force (upwards).

If you do the integral, you will find that the escape velocity of Earth is 11.186 km/s (The kinetic energy is scaled by mass and the force of gravity is scaled by mass too, so mass cancels out)
If you are moving outwards, you lose kinetic energy and speed, but gain potential energy for being higher up and having farther to fall.
Kinetic energy is NOT all energy.

A compressed spring isn't hotter or moving any faster than a relaxed one. And that the stretched slingshot dosen't move either... and how about all that chemical potential energy in your car's fuel tank?