Answer:
Has feathers but can't fly. Rests on legs but can't walk.
Each of these ends in a kettle full of precious metal and the double variety is quite awesome
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.
My life can be measured in hours, I serve by being devoured. Thin, I am quick. Fat, I am slow. Wind is my foe.
At first, I am nothing. Add something to negate. Add again to oppose. Add again to find the time to draw. Add once more to find nobody at all.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?