Answer:
Feed me and I live, give me drink and I die.
I cost no money to use, or conscious effort to take part of. And as far as you can see, there is nothing to me. But without me, you are dead.
Flat as a leaf, round as a ring. Has two eyes, can't see a thing.
A hole in a pole, though I fill a hole in white. I'm used more by the day, and less by the night.
Not a burden for its weight and daily carried out, He who takes it wishes it had never come about
I never sleep yet sometimes I weep. I can get angry or just be happy. Wherever you go, I will follow. No matter what you do, I will be there. I cannot die. What am I?