The mark of the end

Question: I am often known as a symbol/mark, and can be used in a trend. I am created when two paths meet, but separate at the end. What am I?

Question: What tastes better than it smells?

Question: What goes in the water black and comes out red?

Question: What asks but never answers?

Question: To many, I am life's source. I am also its most valuable resource. I create and burn my own precious element, and my destruction will be my punishment. What am I?

Question: I have 6 faces and 21 eyes, but can't see a thing. What am I?