Does this mean that ANZAC can “take” the territory with Fighters? Or it can simply land them there for defense and the territory remains Dutch? For that matter, must UK and ANZAC be at war with Japan in order to “take” the Dutch territories at all?
They must use land units to take the territory and they don’t have to be at war to do so
No. Scrambling occurs during the Conduct Combat phase, so all combat movements will have been completed. Scrambling only occurs in sea zones in which attacking units end their combat movement.
I think if your ship ends up in an enemy convoy zone and survives to their collect income phase it automatically deducts from their total, so that being said I believe you can attack to an enemy sea zone assuming you kill something or noncombat to one. The convoy raiding takes place on the opponents collect income phase so its entirely different from your combat.