Good Riddles

Question: I am god to many people despite not being a spirit. I am what people kill over, lust over, and fight over. I am not God or the Devil, but a mere material that people need endlessly. What am I?

Question: Where do all the letters sleep?

Question: I do good things, but one small push could be a horrid disaster! I am normally used for decoration now.

Question: When the answer I give is yes, it is no, and when the answer I give is no, it is yes. What is the question?

Question: I have two rings. I move by request. If the mixture isn't right I just sit and rest.

What am I?