I do not claim to know all the answers. (Even got my doubts about all the questions.)
However, regarding the question of why disproportionate black representation in prisons:
I have a step daughter and a daughter-in-law who are teachers. Their take on the matter is that some time ago, when racism was even more prevalent than it is today, there came a "break" in society in which black males somehow decided that "whitey" was just always going to screw them, no matter how much schooling was involved. The "Great Society" programs made it possible for black families to live without the support structure of the so-called "nuclear family" - no, that's not a reference to "Bomb the bastards, nuke 'em 'till they glow."
Anyway, with a weak family structure no longer an economic detriment, the old question of nature/nurture became badly unbalanced. The black children, with no strong family figures to provide good examples, feel abandoned (probably with good cause). With no strong family figures to provide guidance into adulthood, they remain childlike, which for an adult isn't so good. Children don't care if they take what is yours; they aren't fully socialized. They get violent. They get cocky. They show no respect. And what we therefore see is a generation that has lost its way to adulthood.
Sadly, the law is required to treat people over a certain age as adults even though they are mentally still children - on a moral/ethical level. So what happens is the law gets tough and the liberal mentality says, "Awww, they aren't responsible for this situation. Go easy on them." And the conservative mentality says, "If we just do nothing, they never learn."
The fact that prisons have more than just black people speaks to the further degradation of the family. The USA "religious right" is strong on the family, which is good, but they carry entirely too much "holier than thou" baggage with them, which is bad.
What's the solution? Damfino! But until we can return that part of our population towards a situation where they can reasonably just "grow up" - we are stuck with them. Can't let them go free, can't kill them and start over, and they don't trust the message of "whitey" regarding what constitutes "adult" behavior. An impasse.
I hope I presented my daughters' views adequately. I about halfway agree with their ideas. Maybe even more than half.