Answer:
You use a knife to slice my head and weep beside me when I am dead.
I have roots nobody sees. I am taller than trees. Up, up I go but I never grow. What am I?
I help engines spin and pants stay up.
I am a king who's good at measuring stuff.
There was a girl half my age when I was 12, now I am 66, how old is she?
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.