Answer:
I am heavy forward but backward I'm not.
You used to come to me for all sorts of information and knowledge before the internet was born
He has married many women, but has never been married. Who is he?
I am a tool for fairies.
I help engines spin and pants stay up.
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.