From age 13 to 20 (boy) or 12-20 (girl), all halachos of adulthood apply. The exception is the implementation of onshin. No one in their right mind exempted them from issurim. If you read that in my comments, re-read them.
Therapy has some benefit to a molester. However, to date, no one has ever been able to demonstrate that treatment reduces the risk of recurrent events of molestation to zero. That suggests that there should be treatment, but that we still cannot depend on it with regards to safety for other children.