The a380 can carry up to approximately 853 people
0 to hundreds -depending on the model
Depends on the airplane. Some really small ones carry only the pilot but some of the really large wide bodies can carry as many as 300.
It depends on the type of airplane. There are small airplanes for only one person and new jumbo-jets that can carry over 750 people in the right configuration. Ultimatly it comes down to wieght. An airplane can only carry as much weight as the wings can produce lift.
525 people in standard three-class configuration, or up to 853 people in all economy class configuration.
2 at a time
In a small airplane up to 3 passengers can be accommodated. This depends on the size of the plane. In small private jets up to 15 passengers can be accommodated.
Two people at most. The first airplane carried its engine and 1 man.
You need a license to carry a firearm in many places. You cannot carry one on an airplane.
About 23 US gallons
Bombardier makes a 50-passenger jet. Some Boeing 747s carry more than 500. The Airbus A380 will carry more than that.
There are many people that improved the airplane. The airplane is still being improved today.