Level Select -
At the Mission Selection screen press the following:
X
Triangle
R1
R2
L2
All Aircraft -
At the Aircraft Selection screen press the following:
Square
Circle
L1
R2
Select
Pontoons -
In Adventure mode successfully complete the Stormy Seas level by landing on an aircraft carrier. The pontoon will let your aircraft land on the water.
Custom parts -
With at least a B rank successfully complete all Adventure mode levels to unlock custom parts.