Long Riddles and Answers

Question: Everyone asks for me but yet everyone hates to face me ,for someone I am agony for others I am relief! Who am I?

Question: Mr. Smith has 4 daughters. Each of his daughters has a brother.

How many children does Mr. Smith have?

Question: I'm in everybody but everybody still wants me.
I won't feed you but I'll feed the tree.

What am I?

Question: I have no eyes, ears, tongue, or nose.
Yet I see, hear, taste, and smell everything.

What am I?

Question: How can you make the following true by adding a single line: .9 = 1.

Note: ≠ is not the answer.