Answer:
I may only be given but never bought. Sinners seek me but saints do not. (one word).
By myself, I'm practically nothing. Worthless as a leader, but when I follow a group, their strength increases tenfold. What am I?
I am lighter than the material I am made of. You see parts of me but more of me is hidden underneath.
Cloud is my mother, wind is my father. What am I?
I am a nut with a hole. What am I?
Give it food and it will live, give it water and it will die.