What Am I Riddles

Question: I drape the hills in white,
I do not swallow, but I do bite.

What am I?

Question: My name can have any letter of the alphabet, but I always have 2 X's.

What am I?

Question: Feathers, I am as light,
But quite heavy if squeezed tight.
I'm seen as clean and pure,
but often talked about with dirty terms.
What am I?

Question: If you look at my face there won't be 13 any place.

Question: I take what you receive and surrender it all by waving my flag.What am I?