What Am I Riddles

Question: What goes on four legs in the morning, on two legs at noon, and on three legs in the evening?

Question: I am a small room,
but no life lives inside,
no matter what weather looms,
very cold my residents reside.
What am I?

Question: I cannot be seen, cannot be felt,
Cannot be heard, cannot be smelt.
I lie behind stars and under hills,
And empty holes I fill.
I come first and follow after,
End life, kill laughter.

What am I?

Question: If you aim to give us a shot, we'll riddle you.

What are we?

Question: Countless blades that bend with a touch,
exploited by kids who want to make a buck.

What am I?