http://en.wikipedia.org/wiki/Dum-dum
No
No, they are not.
Yes, you can find a wide variety of readily available 9mm hollow point bullets and ammunition.
Yes.
No
No, they are not.
yes
yes
Yes
No
Hollow points have a hollowed-out tip that expands upon impact, creating larger wound channels and reducing the risk of over-penetration. Ball point bullets have a solid tip and are designed for reliable penetration and stability, making them better for shooting through barriers or hard targets. Hollow points are often used for self-defense, while ball points are commonly used for target shooting or hunting.
Indirectly, yes.