The word '40' is a mistranslation and should in fact be 'many,' not 40. (That's why you have so many 40 this and 40 that everywhere, should be 'many.')
No, not exactly. The Hebrew word used there that shows up in the King James & others as 'world' is eretz (land). This is one of those cases where it takes a little smarts to figure things out. In the obvious case that the whole world was not flooded, it would be better to translate that passage as just the general land area where Noah lived was flooded. Others have mentioned the olive branch and such, but don't forget the Egyptians and Chinese were around then, circa 2300 BC, and didn't get wiped out, though the Chinese do record a flood about this time in the western province of Xinjiang (Tarim basin, which was an inland sea for nearly 2000 years, also the location of red & blond haired mummies that no one seems to know who they were and where they came from).
It was the whole known world at that time which was flooded. They would not have had any idea if the whole globe was covered or not, not even understanding the concept of the globe or the size of the earth, so the idea of a global flood to them is not the same thing as it is to us.