It occurs at any time
no
Implantation can occur anywhere from 6 to 12 days after ovulation. 5-12 days past ovulation
yes
Yes, for many people it does
Estrogen
LH
after
3days
You bet! In fact, it can occur every month for 30 years.
Yes
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.
Normally every 30 days.