What Am I Riddles

Question: Sometimes I'm high and sometimes low,
and I creep between your toes.
My orders come from the sky,
I make men fall and rise.

What am I?

Question: I wear a red coat and have a stone in my throat.

What am I?

Question: Weight in my stomach,trees on my back,nails in my ribs,it's feet I lack.What am I?

Question: I am a digit, but two of the ten.
Two of me make a promise.

What am I?

Question: When you do not know what I am, then I am something. But when you know what I am, then I am nothing. What am I?