Does the surface or inner parts of the unit get hot?
Not extremely hot, but warm. Cheaper infrared saunas have plates that get very hot and cannot be touched. The plates on this unit, however, do not heat up to extremely high temperatures.
If you are going to use a computer, tablet or phone on the surface of the unit, it’s recommended you get a cooling stand so that the warmth of the wood doesn’t damage your device in any way.