What is black when you buy it, Red when you use it, And grey when you throw it away.

I am related to monuments, but I am not symbolic. People often feel fear with me.

You can sometimes find me on a train or bus. Classical music is my tango, but I adore metal just the same. Either way, I always take charge.

I begin with E and I end with E. However there's only one letter in me. What am I?

I'm not number one and I'm not number three, sit on a throne and below I will be. What am I?