According to the statute that covers this behavior, any person of ANY age having sex with a person under 16 years of age is committing a crime. Read this carefully: §800.04, Fla. Statutes: http://www.leg.state.fl.us/statutes/index.cfm?App_mode=Display_Statute&URL=Ch0800/SEC04.HTM
You may also want to look at: §827.04, Fla. Statutes (Contributing to the delinquency or dependency of a child) at: http://www.leg.state.fl.us/statutes/index.cfm?App_mode=Display_Statute&URL=Ch0827/SEC04.HTM
This 17 year old NEEDS an experienced local lawyer who specializes in criminal law.
First, it is not against the law to date, but it is against the law to engage in any sexual activity with a person under 16 years old regardless of the age of the other person. The law for 16-24 would not apply in your situation because one party is only 14 years old. A person under 24 can have sexual relations with some older than 16. For example, it would not be illegal for a 22 y.o. to have relations with a 17 y.o.
As to the other question regarding the 17 y.o. and no prosecution, the answer is no. The State can file on a person as an adult if they feel the charges are not appropriate for a juvenile disposition.