Can scrambled planes choose not to return to the territory they scrambled from? (Assuming there’s place for them on friendly carriers in the seazone they scrambled to)

Thanks for the quick reply to my previous questions, got some more:

1. “An additional 2 PUs per each “open” Lend-Lease lane, when Russia is at war with European Axis, if Japan has also declared war on Russia.”
I assume this means an unprovoked declaration of war by Japan? Russia can’t trigger this by declaring war themselves?

Next two are not necessarily about BM3, but they came up since BM3 gives Russia and Japan incentives not to declare war on each other:
2. When Russia and Japan are not at war, can Russia land its planes on Allied carriers in the Pacific? Can UK/ANZAC land planes on American carriers when the USA is not at war (or when both are not, in case of the Pacific board)?

3. (Disregard this question if the answer to 2 is “yes”) There’s a Russian plane on a British Carrier on the Europe board. Russia and Japan are not at war. UK tries to move the Carrier to the Pacific board. What happens?

Apologies if this has been asked before. I’m a little confused about what exactly happens in what order if the Vichy Armistice is broken.

The situation: Vichy France has been activated in a previous turn. Italy takes a North African Vichy territory and Southern France.

1. Does he fight the defending troops to conquer Southern France, or is it Pro-Axis enough to just walk in and annex it?
2. If no fighting occurs, do the troops in Southern France join Italy? I’d assume not, but a literal reading of the rules implies they do.
3. Does Italy get the troops in North Africa? As the rules say the rest of the troops are disbanded at the end of the turn, and Italy annexes it before the end of the turn, I’m guessing yes? Feels wrong though.