Atheism is just as illogical as theism. You can apply Occam's razor to assume that there is no god/gods, but that is still just that, an assumption. Agnosticism would be the logically/scientifically backed argument.
No, it's not. Unfalsifiable deities are unscientific. So being an atheist against any kind of unfalsifiable deity is scientific. And all religion is unfalsifiable by definition.
That is stupid logic. The possibility of a potato controlling everyones' mind is not zero.
There is nothing that indicates a god exists, hence no reason to believe it. The scientific way would be to belive it if it was possible to prove, but since it is not and there is nothing to indicate otherwise, atheism.
Typically, atheists don't spend a lot of time thinking about gods. Also, most theists aren't just theists, they follow a very specific religion/god, which is orders of magnitude less reasonable.