Answer:
My life can be measured in hours. I serve by being devoured. Thin, I am quick. Fat, I am slow. Wind is my foe.
My first is an insect; my second is a border; my whole puts the face in a tuneful disorder.
Used left or right, I get to travel over cobblestone or gravel. Used up, I vie for sweet success, used down, I cause men great duress.
I can sizzle like bacon, I am made with an egg. I have plenty of backbone, but lack a good leg. I peel layers like onions, but still remain whole. I can be long, like a flagpole, yet fit in a hole.
Without a bridle, or a saddle, across a thing I ride a-straddle. And those I ride, by help of me, though almost blind, are made to see.
People take me on walks and I run and have fun. What am I?