Which part of the electromagnetic spectrum have the highest level of photon energy

The energy carried by one photon is directly proportional to its
frequency.  So the photon energy is greatest for the electromagnetic
waves with the highest frequency / shortest wavelengths. 

That's why when you get past visible light and on up through ultraviolet,
X-rays, and gamma rays, the radiation becomes dangerous ==> each
photon carries enough energy to tear electrons away from their atoms,
ripping molecules apart and damaging cells.

The photon with the highest energy is a gamma-ray photon.

The objects do not reach terminal velocity         there is not enough time from the time the object falls from when it hits the ground to achieve terminal velocity. an object must be placed higher to achieve terminal velocity in order to be in free fall.