The Elementals

Here is your riddle:
I am greater than god.
I am more evil than the devil.
The poor have me,
The rich need me,
And death comes to
those who eat me.
Who am I?"
***
I am ever hungry,
And live if you feed me.
I am never thirsty,
And die if you quench me.
What am I?"
***
I see much, but change little.
I am firm, irresolute,
Powerful, but gentle;
I have enough strength to
rip apart mountains,
Yet be moved by gentle stirrings,
I am life itself,
And I give life to others.
Who am I?

I'm a five letter word that has no end,
One through three can amend,
One, four and five are
something alive,
Two and three occur near thee.
What am I?"
***
I am light as a feather,
Yet no man can hold me for long.
My presence causes life,
My absence death.
***
"I welcome the day with
a show of light,
I steathily came here in the night.
I bathe the earthy stuff at dawn,
But by the noon, alas! I'm gone."
***
"The last, but not the least, little one:
Lighter than what I am made of,
More of me is hidden than is seen,
I am the bane of the mariner,
A tooth within the sea.
Speak my name.