Gone in a flash

Question: Once you are in my sight, you are gone in a flash, and people tend to use me for cash. I am often used as a dire assist, and people often believe that I cause harm, when I am but its catalyst. What am I?

Question: Resurrected, they descend by the millions. Sometimes, to nourish and give life. Other times, to take lives or destroy. They have been known to fill entire valleys and block roads only to disappear before executing their long journey back to the top. What are they?

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