Answer:
I am wood that is neither hard straight or crooked
I hold two meanings. With one I may be broken, with the other I hold on. What am I?
What has no beginning, end, or middle?
Iron roof, glass walls, I burn and burn but never fall. What am I?
The more you take the more you leave behind. 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.