It lit. means "the happiness comes out from the tip of the eyebrows". It refers to when someone is so happy that it is totally clear from his/ her face.
It lit. means "actually it is not right". It is used to say that something is actually not how people think it is, so it is used to make a contrast, and it simply means "actually this is not so".
功成身退
功成: "success"/ 身: from 自身, "oneself"/ 退: "to step back"