I am playing the axis and allies 1941 version and I am curious to know what do the factories do and what happens if an enemy claims it

@barnee I am playing the axis and Allies 1941 (not anniversary edition)
Also one more question what is the point of factories in the axis and allies 1941

1.Does it cost a move to do an amphibious assault if you’re already in that sea zone that is neutral. For example I’m want to attack Australia and my allied ships are already in the sea zone that has Australia
2. Can infantry attack battleship