Logic Riddles

Question: A married couple went to the hospital to have theit baby delivered. Upon their arrival, the doctor said he had invented a new machine that would transfer a portion of the mother's labor pain to the baby's father. He was asked if they were willing to try it out. They were both very much in favor of it. The doctor set the pain transfer to 10% for starters, explaining that even 10% was probably more pain than the father had ever experienced before. However, as the labor progressed, the husband felt fine and asked the doctor to go ahead and kick it up a notch. The doctor then adjusted the machine to 20% pain transfer. The husband was still feeling fine. The doctor checked the husband's blood pressure and was amazed at how well he was doing. At this point, they decided to try out for 50%. The husband continued to feel quite well. Since the pain transfer was obviously helping out the wife considerably, the husband encouraged the doctor to transfer all the pain to him. The wife delivered a healthy baby with virtually no pain. She and her husband were ecstatic. When they got home, the mailman was dead on the porch.

Question: A cowboy rode to an inn on Friday. He stayed two nights and left on Friday. How could that be?

Question: The more you add, the less it weighs.

Question: There is a chain nailed to the wall. The chain is 10 feet long and the center of the chain dips down 5 feet from where each side of the chain is nailed to the wall. How far are the 2 ends of chain from each other?

Question: A natural state, I'm sought by all.
Go without me, and you shall fall.
You do me when you spend,
and use me when you eat to no end.

What am I?