This is why you can recieve radio waves through a stone wall. This same wall, however, will block the shouts of somone outside. If it has a large enough magnitude it can knock you off your feet. An electromagnetic wave is not physical. If it is powerfull enough it can effect the molecules in your body but it really can't push you over in the same way a sound wave can.
Humans can definitely hear that.
That is a measure of the magnitude of the wave. It is basically how loud the sound is. Just to give you a rough idea of noise level the sound in the cabin of a jet plane is about 80 dB. See below for a discussion of what a dB is. When it is said that a sound has a certain dB, it must be compared to some standard. So an 120dB sound has 3.2 times the amplitude of an 80 dB sound.