Ovulation occurs in the ovaries.
Implantation can occur anywhere from 6 to 12 days after ovulation. 5-12 days past ovulation
Yes, for many people it does
It occurs at any time
You bet! In fact, it can occur every month for 30 years.
Ovulation does occur before menarche. Menarche is the term used to describe a girls first period, menstruation will only occur if the woman ovulates. With that said some people will experience vaginal bleeding as a result of hormonal imbalance which will look like menstruation but without ovulation occurring beforehand, and sometimes we call that menarche - because we've no way of knowing if ovulation had occurred.