A riddles crossword

It goes up and down the stairs without moving.
The more there is, the less you see.
The more you take away, the bigger it gets.
It goes around the world without leaving its corner.
It comes up and goes. It comes down and stays.
What is between in and out?
It goes up when the rain comes down.
It's full of holes but still holds water.
What do you answer even though it never asks you questions?
What word is always pronounced incorrectly?
The first planet discovered by man.
Name a palindromic time of day.
What word becomes shorter when you add two letters to it?