Cancer is your own body doing it's own thing. Cancer isn't a foreign invader, it's your own cells/body doing the damage. Other than a small amount of viruses that can potentially cause certain cancer (HPV being the main one), or inheriting certain genes from your parents, cancer itself isn't passed from person to person like bacteria or a virus is.

No.

Though you can get infected with anything she might have, just the same as anyone else's needles.

Good luck

Dave