Hmmm..... mostly human, you ask quite a few 'difficult' questions there! Probably the most difficult ones that Mankind has asked since we started to think and question anything... but I'll have a go at answering, based on my personal experience as a medium and a failed suicide, which has maybe given me a little insight?
When you die, you are permanently and irrevocably separated from your earthly body... which is the part of me writing this, as is the part of you who pressed the keys to leave the Q I am trying to answer. Stating the bleedin' obvious, but have to start somewhere?
AFAIK, and according to everyone I have asked - whether dead who I knew, dead who I didn't, and probably never dead at all, but living in the same realm - when you die and leave your body, any pain, disease, imperfection or discomfort associated with the body - even depression, addiction, dependency and mental disability - is left behind, and rots, burns, is eaten or mummified with the physical body, which can no longer trouble you. However, the possible long term effects of such misery, pain and despair can accompany you for a while 'in spirit', having affected your 'spiritual character' very deeply, and for a very long time sometimes. I don't pretend to understand how this is organised, by whom or what, or how it is achieved, but these persisting imperfections and 'hang ups' don't usually last long, and are 'healed' by methods I am unaware of, and can result in a 'rest period' of indeterminate length... I only know of one example, which took a couple of years. Years to me - time is irrelevant on the 'other side', it doesn't work like that we know, e.g. 1second/second/ hour/hour etc etc. There seemsto be no suffering involved.
This of course only applies to those who have died and made a 'clean break' from their earthly body. Break your neck, and you could still be alive, in more helpless pain than ever! Be careful....
With reguard to quantum physics, I have a suspicion we are about to see some mind-bending new revelations from the Hadron Collider MKII, but will evade my understanding. There is a book however, which might explain a lot - "Psycho - Electrics" by John Ivimy. Good luck.... if you manage to understand the stuff about 5D geometry, please do tell!