It says Jesus is the Word of God and all that was made was made by him. God spoke and there was light. He spoke what? His word his word was Jesus and made flesh among us, the very power of God made in fleshly form made a son of man through the flesh but was in fact the son of God. Yes God has many sons as you stated. But none were made without sin as God has no sin other than Adam in the beginning and Jesus but Adam fell and Mary was a virgin, no other son of God was made with only a woman and God himself this makes him the only begotten where God used a human being to bring forth his son in the flesh. Adam wasn't from forever, Jesus was with GOd before the beginning as we know it this does make him the only begotten for the Word was always with God Adam was created Jesus ( the word) always was and is. And God sent his word.3 days signifys death burial and ressurection. He told his disciples he would die. Just because he ask God if there be any other way does not show that Jesus didn't plan to die, he showed his was willing to do what the Father required of him but yes in his body and soul ( not spirit) he sought for another way not so much because of pain but from being separated from his father. He did not want to be separated from his father. Remember God is love, He would be separated from Love and the spirit would fail him. That is why he ask GOd why have you forsaken me. He took on all the sins of humanity he was void of God for that moment he was just a man on a cross without the spirit father God with him. Like a person who isn't saved is without God. But God ressurected him and did not leave his soul in hades nor allow his holy child to see corruption. I studied the 3 days 3 nights before and found a answer but I will get back to you on this because I forgot exactly how it went. I know it had to do with the way the Jews count days their evening and their night. If I remember correctly it would put Jesus rising on a Saturday ( Sabbath) and they went early to the tomb before sunrise but It may in fact be sunday so I need to go back and try to find out how I figured this out.