First, a version of eternity you experience in the moments before your brain dies—like a dream—then eternal sleep.
Nothing. It's the same as what happened before we were born.
All of the humans are reincarnated as insects, all of the insects are reincarnated as humans, and no one remembers their past life.
Part dies and part lives. If you have kids, your DNA lives on without the useless memory, otherwise just part of your mind is left.
The soul of man is immortal and imperishable.
I do not believe in immortality of the individual-Since our inner experiences consist of reproductions and combinations of sensory impressions, the concept of a soul without a body seems to me to be empty and devoid of meaning.