Good Riddles

Question: The more of me you have, the longer your life.
The more of me you have, the less you have left.

What am I?

Question: My eye is dark,
and my mane is yellow.
You man see me at the mart,
and I'm probably taller than you fellow.

What am I?

Question: A man runs into a bar and asks for a glass of water. The bartender pulls out a shotgun and yells at him. The man thanks the bartender, then walks out of the bar happily.

Why did the man thank the bartender?

Question: A claustrophobic person gets on a train. The train enters a tunnel just as it is leaving the station.

Where is the best place for him to sit?

Question: The first is a sign of something good,
the second says whereto;
the third is vulgar and mean,
the fourth is bound by a ring;
the fifth is the noble one.
Together they all drum.

What are they?