I'll give these questions a try, hell... I believe in hell.
1. Yes, it is perfect justice. We are talking about 120 years of knowledge, you would figure by that time you would know sinning is bad.
So if a souls finally gets it after 12000000 years of torture, what is the purpose, other than plain old cruelty in continuing with the punishment?
It has repented and been rehabilitated.
2. Sin has 2 sections. Intentional and unintentional. God says if it was a mistake you may be forgiven. Anything you do with your hands and your mind is on it, that is what will cost you.
A dodge.
Describing what sin is does not in any way answer the question of graduations or the severity of sin.
3. Is it good justice to keep a psycho serial killer in prison for life? Or to be let out with common folk even though he won't get any better for the rest of his life?
What does this have to do with hell?
4. No, it would not be. God said the way punishments go after we die. If I kill and rape as many people as I could and I know that when I die all I get is nothing, no pain, no punishment I just turn off. That doesn't justify the pain you have caused to countless families.
I did not ask about God.
I asked if it was good justice.
Hell was created by God for a fair reason, you just have to understand the circumstances and get passed yourself.