About 3: In many countries life doesn't have to mean life but still gives the vague chance for release. For example in Germany "life" means an absolute minimum of 15 years (+ 5 years on parole), on average it means about 19 years (often + years of parole). The basic idea is that the older you are, the less likely it is that you do the crime again and the more likely it is you can live a peaceful life as normal part of the society again. This doesn't mean life sentence isn't enforced though, as the average I mentioned only included those who were actually released. About 1/5 die in prison, the duration of their prison time is not part of that average (I don't have better numbers at hand). The current record setter was released (on parole) this year after 59 years in prison. Additionally, after "prison" many are set into preventive detention, which still means prison, but under better conditions and with better chances to be set free again completely. However it is an unconditional rule in Germany that every single prisoner must have the perspective to be set free one day.