i would rather discuss those things in private...with the atmosphere as it is i think things could get out of hand too fast...
i will answer one:
Who actually wrote the "Old Testament"? The Jews? The Muslims? Christians weren't exactly in place at that time....no offense to Christians.
The Jews and Christians would say that God wrote it through Moses and the Prophets to the Jews...true Christians had not shown up yet and Muhammad ibn 'Abd Allāh did not arrive until 570 years after Jesus.

Let all bitterness, and wrath, and anger, and clamour, and evil speaking, be put away from you, with all malice:And be ye kind one to another, tenderhearted, forgiving one another, even as Elohim for Yahushua the Messiah's sake hath forgiven you. Ephesians 4:31-32