Correct - the hanger can only accommodate the biplane. That having been said, in order to accommodate the other aircraft too the hangar would have to be huge, with an enormous footprint, and a substantially increased parts count. As a result, I'd estimate a price up to double the current RRP which I suspect few of the target market would pay. LEGO therefore got the size of the hanger right IMHO.
The first few bags build the small truck with carts that you see on airport runways. The truck has a "follow me" sign that I confess I have not seen at any airport. There is also a fueling tank and a rolling staircase that sits next to the plane to allow for boarding. Both the tank and the staircase are additional carts for the truck, though I am guessing not both at the same time.
The airport handles an average of more than two million passengers a year, and millions of pounds of cargo. The airport's main runway can handle airliners as large as the Boeing 747, although most passengers arrive on smaller aeroplanes, such as ATR-42s, Boeing 737s and Boeing 757s. Boeing 747 activity at this airport is almost exclusively limited to cargo flights.
The remainder of the build is the control tower and terminal building. First there is a metal detector screener leading to the waiting/secure area of the airport, which seems taller than it needs to be for the minifigures. I think the same effect could have been made with half the height, except that would not allow for an impressive height for the overall tower. However it does seem to be similar to many modern airports with the high ceilings. This area also seems to be someplace to check luggage as evidenced by the rather nifty conveyor belt that comes in a full part. The moving parts of the set include a revolving door (a very tall one, for the first floor) that leads from the secure area of the airport out to the tarmac, and of course the conveyor belt.