No. That was during the old times so they just age and die but she's immortal. Also, if she wanted to go back to those countries, she could have just changed her appearance.
Yup. The book doesn't say much about other witches but they do mention one and she was the one who teaches Kendra (the witch who gets kicked from other countries) all about witchcraft.
Nope. Just Kendra and her brother shoving the afore-mentioned witch into the oven. Kinda like from Hansel and Gretel.