[rust]

I can only answer that based on my experience with a fighter-bomber unit of the German air force, it may be different elsewhere.

[*]In which type of structure–shelter or hanger–would a plane most likely be found in the few hours prior to taking off on a mission?

In or in front of its shelter.

[*]Is one type of structure is more likely to contain the overhead lifts, offices, workspaces, etc.? I assume the hangers.

Yep, the hangars. They have all the technology for maintenance and repair,
and are usually large enough to service two or more aircraft.

[*]Which type of structure is the more common?

The shelter. The unit had one shelter for each of its aircraft, but only two
hangars.

[*]What are typical sizes?

The shelters for the type of aircraft our unit used where not much larger
than the aircraft itself. Here is a typical picture:
http://www.creativecrash.com/system/...jpg?1251149976

The hangars were much bigger, in fact big enough to be used for all kinds of
ceremonies and celebrations for hundreds of people.

[*]In general, which type of structure are military planes more often found in? How many planes?

The shelters, this is where the aircraft are normally kept when not used. The
number of shelters on an air base depends on the type and size of the unit
stationed there, in our case there were 12 active aircraft and a few reserve
aircraft.

My impression is that the shelters are beefier, but simpler and cheaper and more common. If a plane is in a hanger, it's there for some other reasons besides mere storage, e.g. maintenance, either just prior to and just after flight.

Right.