Answer:
I am heavy forward, but backward I'm not. What am I?
What is black when you buy it red when you use it and gray when you throw it away?
What do people spend a lot of money on every year, but never want to use?
I may be of the eye, in order I am pie. In my center there is a star, I keep medics where they are. What am I?
I help engines spin and pants stay up. What am I?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.