"How can I forgive an abusive pastor?"

Is it okay for the church today to use musical instruments for worship? Why did Peter put on his coat (or garment) before swimming? How can I forgive an abusive pastor from my past? How did John the Baptist not get killed as a baby by Herod's edict? I heard that what God wrote on believers' hearts only becomes true if we study the Bible enough. Is this true? How will we not be sad in Heaven when some people whom we love are not there with us? What did Jesus mean by, "I have overcome the world"? Was the thief on the cross actually saved?