Lower pay than private industry jobs. Very strict standards/background req's. Placement across US.
Sometimes world depending on the agency.
If you want to do it; its something you will strive for and have to be very good to get into those...Depending on your education, you could possibly get in without law enforcement experience, but most likely not unless you have a CPA/foreign language skills/IT security certs/foreign relations experience.
FBI generally will not hire under 27 years old. Customs will pick up inspectors and border patrol around 20-22 depending on experience.