The wave length of the rays is classified as infrared rays, visible rays,
ultraviolet rays and X-rays in order from the longest. Ultraviolet rays are utilized
mainly to the dermatological treatment as its length too long to penetrate into
the skin. As a kind of wave energy, the frequency ranges of infrared rays
in 0.76~1.5 microns are called near infrared rays, 1.5~5.6 micron rays are
medium infrared rays and 5.6~1.000 microns far infrared rays. A German
physicist(The Nobel Prize Winner) proved that infrared rays with the frequency
ranges between 6~14 micron are effective to ionized heat treatment.

About 5,000 hours.

Yes, it is also easy to be mounted.

Heat can be instantly made upon switch-on.