Good Riddles

Question: For now I must stay under the man who made me,
but when he dies I'll be as powerful as he.
They will watch and listen to what I say,
then some of their money to me they'll pay.

Who am I?

Question: In a marble hall as white as milk, Lined with skin as soft as silk, Within a fountain crystal clear, A golden orb does appear, There are no doors to this stronghold, Yet thieves break in and steal the gold. What am I?

Question: Using 3 periods (.) and 1 question mark (?) make this a logical and grammatically correct sentence:

"That that is is that that is not is not is that it it is"

Question: Travel a mile and I will change.
Travel a million and I will end as I started.

What am I?

Question: I can be seen, I can be not. Thanks to me, you'll fall in love. I mostly am sweet, but once I were sour. You can receive me, you can't just buy me. You only can send me, or simply share me. What Could I be?