YES AUSSIE JAPAN WAS GOING TO INVADE AUSTRALIA AND USA SAVED YOU!

yes japan had plans to invade Australia. Read the book "Victory in Papau" by the US Army!
In it the Japanese, thru their plans and correspondence, stated first Port Morseby. Then Fiji, Samoa, and New Calendonia would be secured. Australia would be cut off by 1943. Then they would move on Queensland and the Eastern side. They hoped the US Navy would be finished off by then or that the US would negotiate so they could keep their conquest.
But Gen. MacArthur sent troops to Port Morseby, then launched a counterattack at Buna with American troops. Queensland was also fortified heavily. With the success of Americans on Guadalcanal and Buna, the Japanese were put on the defence. With American airpower, and naval dominance the threat to Australia was settled.
Besides if the US Navy had not won the battle of the Coral Sea, Port Morseby would of been occupied and Queensland would have been next!