Is it at all possible to detect all air type signals for a given location? For example, if I wanted to get a list of all air signals (i.e. wifi, bluetooth, radio, 3g, 4g, and all other air type signals, gps etc) going into and out of a building, is that possible?
It's very hard, but you can identify some sources. You can scan for the common types (GSM, Wifi, etc), but there's no way to tell a encrypted low-bandwidth signal from noise.
Even if you get a very wide band scanner (from kHz to GHz), it's almost impossible to identify every channel entering a building.
Signals exiting a building can be easier. You will have to use a wide band scanner, scan around the building and create a profile of the radio signals around. Then walk around the neighbour buildings and take note of the difference in power on all bands. If you see a band fading, use a directional antenna to see if the transmission is really coming from that building.