Pondering water

I IMAGINE that most local residents have had enough of rain. But just imagine had it been snow! Anyway, what I would like to know is: (1) Is there as much water (and ice) on the earth today as there was when the world was first formed? (2) How did it come about that fresh water fills the lakes and rivers on land, and salt water fills the seas? (3) How is the balance between fresh water and sea water maintained when it is only fresh water that falls onto both the land and the sea? I am hoping that one of your more erudite readers, of which there must be many, can provide the answers, if possible in a letter of less than 300 words.