Answer:
I am free for the taking. Through all of your life, though given but once at birth. I am less than nothing in weight, but will fell the strongest of you if held.
What English word has three consecutive double letters?
The more you take, the more you leave behind.
This thing all things devours: Birds, beasts, trees, flowers; Gnaws iron, bites steel; Grinds hard stones to meal; Slays king, ruins town, And beats high mountains down.
What is eaten but not grown and was born in water but will disappear if soaked?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?