Like the letters provided for this liddle

Use me to describe a person, a story or length of time. Not tall, but like this riddle.

I appear when water is beaten, yet I am lighter than what I’m born from. I cling to shores, mugs, and mouths, a crowd of tiny prisoners made only of air. I vanish at a touch or with time, but while I last, I soften every surface. What am I?

White crystals that make flavors bold, In oceans deep and mines of old, A pinch of me, your dish is sold, Without me, bland stories unfold.

A two-wheeled transport from the past, To add two more, remove my last. Different beasts can steer my course, But don’t put me before the horse.