God the Father sent the Son of God, Jesus Christ, to the cross as the holy, infinite sacrifice necessary to satisfy God's infinite, holy nature against the sin of humanity. Here "Son" is an important title for Jesus, the Son of God. (See: [[rc://en/ta/man/jit/guidelines-sonofgodprinciples]])
Paul is using a question for emphasis. Alternate translation: "he will certainly and freely give us all things!" (See: [[rc://en/ta/man/jit/figs-rquestion]])