these questions are not all clear, and are perhaps explained in FAQ.
Air Defense: Whenever an undamaged carrier is attacked, its aircraft (even those belonging to friendly powers) are considered
to be defending in the air and fight normally, even if only submarines are attacking and the air units cannot hit them because
there is no defending destroyer
Combat: […] If a power at war attacks a
sea zone containing units belonging to
both a power with which it’s already at
war and a power with which it’s not at
war, the latter power’s units are ignored.
Those units won’t participate in the
battle in any way, and a state of war with
that power will not result.
I would therefore guess that the planes take off, and can land in any friendly zone next to the combat. but I am not certain in any way
The planes are definitely allowed to use one move to find a landingspot. it is even given as an example in the rules.
3. Only defending fighters gets the “extra” move to find a landingspot. If your fighter have used its 4 moves, it is done. However, your AC has to try to save your fighters if the can.
4. As I understand it, your scrambled planes have 1 move from the seazone they scrambled from, not from the landzone where the AB was.
5. The transports can retreat. Any transports that are hit in the first round of combat dies tho. So, if you are attacking with 3 ships and 5 TTs and the defender gets 4 hits on you. You will kill all three ships and 1 TT, the final 4 retreats.
7. They are like Pro allied with benefits. The benefit being that you can land Airunits there without having activated them yet. The other benefit, is that if Japan attacks them, they are at war with UK and US can declare war on Japan.