The answers to these 2 questions subject to the Hell and Heaven's definition. Let's look the definitions of hell and heaven that I get from a dictionary:
- The world of the dead where you're being punished and suffer.
- A place beyond the sky with great happiness, delight, or pleasure
So, do hell and heaven exist?
Yes but not necessary the hell or heaven is a place, it could be just a condition.
By the way, when you're Hell doesn't mean you will be forever in Hell. Same to when you're in Heaven, will you be forever in Heaven? No, the suffer and happiness will end and restart. When the suffer restarts, it could be no longer suffer. When the happiness restarts, it could be no longer happiness. Everything is looping, remember?
P/S: After death, we move to another milestone but it is not necessary a hell or heaven. It could be something else and it doesn't really matter because it is merely just another milestones.