Those are great questions, Foogirl. Would it make a difference if more were to be spent on education, thus creating more opportunities when kids reach adulthood. Would those opportunities be more likely to keep people from commmiting the crimes which send them to jail?
I do believe the costs of incarceration are similar regardless of the offense and type of facility. Standard things need to be covered across the board: food, utilities, prisoner health care, staffing, ammo, weapons, bedding, cleaning supplies. Then there are also classroom opportunities, so outside teachers and books/materials need to be paid for. There are transportation costs: vehicles, fuel, additional guards, sometimes airplane usage (which is pricey). Plus any rehabilitation programs. Then there is the salaries of the parole board, which I'd assume is paid by the prison system (don't know for sure)?
Some of the super-low security facilities, called "camps", also provide their inmates with daily newpapers from all over the nation. Hell, I don't even have one newspaper subscription!!