You have got pretty valid points here.. Leaving aside everything if anyone has problem of the age of marriage the times were different and it was common on those days
In Islam it is believe that Jesus did not die but he was lifted up in the skies still living, and he will return as a messiah to fight the anti christ..
Yes, I do believe it exists and medical says that the weight of the body is even decreased after the death even though some says it's because of the things that our body releases but spirit might be another one of the reasons