Hi Mitch,

IMO the additional enclosures are not needed, but they surely bring additional protection to the unit. To answer the questions:
– The model A units were effectively tested in the -20 .. +65 Celsius interval with no impact on their functionality. That is -4 .. +149 F .
– No. Thin plastic enclosures are transparent to Gamma radiation.
– No, but care should be taken, as increasing the temperature over +65 might degrade the magnetic properties of the ferrite core, resulting in the high voltage inverter being unable to supply the required voltage to the Geiger tube. If you compare existing charts, you’ll see the direct link between temperature and the inverter’s duty cycle parameter – quite interesting.
– Free air no, but outdoors yes, as that is where a possible contamination can come from.
– Interesting question. In case of a nuclear incident, fallout covering the ground will be registered by the detector. Intensity varies with the square distance to the source. So the height requirement is in place to ensure consistent response all across the network, but if such an event occurs, this is the last thing to worry about. Snow can be disregarded, even if it affects the height, it is temporary.