What Am I Riddles

Question: Cold and dark, I'm the same as my neighbor. Flatter than a pancake, faster than a panther. Lighter than a feather I still prevail, Yet a million mean trying to lift me would fail. Expanding and shrinking throughout the day, When heat is highest, underneath I lay. I leave in the darkness of the night, And don't come back if there's rain in sight. What am I?

Question: Something all men have,
but all men deny.
Man created it,
but no man can hold it.

What is it?

Question: What's small like a mouse but protects like a lion?

Question: I'll amuse you for an entire evening, But you won't remember me. What am I?

Question: Not only a seat, it’s also a head - what is it?