If by "sexually immature" you mean "homosexual", then yes.
Not necessarily. Keep in mind, not ALL of the victims of abusive priests were male although most were.
By sexually immature, here is what I mean: Even though a young seventeen year old may have felt a strong calling to the priesthood, does that mean such a young person is mature enough to comprehend the Church’s strict policy with regards to celibacy.
Celibacy is a tough discipline. While valued and appropriate, it must be made by a fully mature individual capable of comprehending it and living by it.