"American Capitalists", "Yankees", "GI's", and "Yankee Imperialists."
The war to end all wars
Because Hamburg is a city in Germany and America was fighting Germany during WWI.
tomodachi
Okinawans proudly call themselves uchinanchu (沖縄人) or "sea people" in the local dialect
No more than Americans when you call them Yanks, or the British being called limeys. By the way it is krauts not kraults, first used in the first World War as a derogatory term for a German soldier. It was as a synonym for sauerkraut, a traditional German and central European food.
Joseph Stalin
You may say 'nisei.' 二世
The japanese imperial army
the Japanese expansion of the 1930s was to expand out of Korea and into manchuria which it annexed and call manchukou
Japanese and the Russians
the continentals
yes
there is a mission in call of duty world at war where you have to fight at sea against the Japanese
the Green Machine
The Imperial Army
The war to end all wars
Yes. It depends on where you live in the world, because in the UK, "corn" is what US Americans call "wheat". In other parts of the world "maize" is the most common name for what US Americans call "corn".