Regardless what you believe this made laugh (I don't know why)

Hundreds of billions.

I think so but not at like a meth or crackhead level.

It really depends on the person. I know some who can smoke tons then go months sober and others who can't stop.

From what I've learned, you can't become physically addicted like tabacco/alcohol. It's a psychological addiction like being addicted to gambling or masturbation

I suppose so. In my experience it's a lot harder to go without alcohol than it is weed, but at the same time I was able to give up tobacco pretty quickly. I think it really varies from person to person.