1- Why would you need an afterlife, when this life so beautiful? If you can understand D.N.A. then you would never need something childish like an afterlife.
When one is dying, the only part of the brain functioning is in the core or the primitive part of your brain. Hence, you seeing "the light" because the upper part of the brain isn't processing anything, happens when the visual portions of your cortex are being stimulated but there's no processing going on to interpret what you're seeing.
2- I think this only works on LeBron James.