Troy555,
You were just given a goldmine of advice here by Sr. members who dissected your questions. I would add that my $0.02 in regards to your wondering about State vs the FBI. If you go into a state police career, you will learn the A-Z of police work, and more than likely experience it also. With Federal LE, it focuses on specific mission objectives that will see most of that agencies efforts concentrated on. Both have merit and valid career fulfillment, but are unique in what they do. I firmly believe that the more real police work you get under your belt, the better you will be in investigations.
In a police department, you don't see 21 year olds joining the force and instantly becoming Detectives, but you can do that essentially with the government as a Criminal Investigator.
You have loads of time to research your options, so good luck.
"Kid, I've sat on the department ****ter longer than you've been a cop." (CatDoc to Chevy SS, the single greatest post ever on RP!)
Moon Pies and RC Cola make me happy