1. Now I am aging one hundred.
  2. Now I am one hundred years old.
    Does both sentences mean the same?
    How the natives use #1?

Only the second sentence is correct.

Can I say: “Now I am aged one hundred.”?
He is an aged man.
The aged people can apply for old man pension.
Are you aged? But You look young.
What is your age?
As age passes, the man become weak.
Are all these sentences OK?

Now I am aged one hundred is okay.
What is your age? is okay

He is an aged man is just about passable.

Your other uses of ‘aged’ are odd as there is no way of defining what age you mean. You could say ‘old-age(d)’