What Am I Riddles

Question: I have four feet in total, two that I stand on and two that I don't . What am I?

Question: Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.

Question: I live in your house yet, you do not love me. I eat your food, yet you squeal in fright at the sight of me. What am I?

Question: Act in my name, and thus remove me. What am I?

Question: I have no wings but I fly,
I have no teeth but I bite.

What am I?