It is false it has straight sirface
Free fall condition : acceleration is constant downward and equals to gravitational acc.(g)
because velocity has opposite direction to acceleration, velocity will decrease as it rises.
Weight can be explained as the force with which the gravity pulls an object. Your weight will not be the same in all planets. In moon, you will weigh far lesser than how much you weigh on the earth. However, in earth and in the moon, your mass will remain the same.