Q1. From how large a group of people does God remove sins in Isaiah 52:13 - 53:12? In what sense is this a universal sacrifice of salvation?
The Son of God, our Jesus Christ, is the perfect lamb in exchange for our freedom. He is the perfect sacrifice that is worthy as an sin atonement for all nations, till the ends of the earth.
For those who have ears, let them hear, and those who have eyes , let them see. The Son of God offers salvation to all who accept Him as their personal savior and offer up their lives to Him. Seek not our Kingdom but His Kingdom, and in everything, put God before us, until we unite with Him in Heaven. God's salvation plan is to provide a way for us as sheep to unite with the Shepherd. Jesus finished work is a testimony of forgiven sins and the fulfillment of God's will. He trump over sins and sit at the right hand of the Father's throne. He has become our intercessor until today, and until the end of the earth.
In what sense is Jesus' sacrifice wasted on some people?
Those who rejected Jesus, rejected their own lives. jesus is the bread, the life and the way. Without Him, we will not be able to enter our Father's kingdom. Jesus work is never wasted because His victory is forever.