I assume you are speaking of the Book of John. Yes Jesus is God, and yes God died for our sins. All of this to have us from God's wrath.

'Will'? No. That job is done. Why should it need to be done again?

essentially christians do believe that their God did in fact die upon the cross for the benefit of humanity

great question!!! my understanding of religion has revolutionized since i myself have become a father. a part of me dies each time i see my own children "sin". a part of me would die so that my own children might live or might even lead a life of which i would feel honored. jesus did something of which every father might be proud. god, the father, needn't die "a second time" for your and my sins, in my opinion.

The person who became known as Jesus Christ did not begin life here on earth. He himself spoke of his prehuman heavenly life. (Joh 3:13; 6:38, 62; 8:23, 42, 58) John 1:1, 2 gives the heavenly name of the one who became Jesus, saying: “In the beginning the Word [Gr., Lo′gos] was, and the Word was with God, and the Word was a god [“was divine,” AT; Mo; or “of divine being,” Böhmer; Stage (both German)]. This one was in the beginning with God.” Since Jehovah is eternal and had no beginning (Ps 90:2; Re 15:3), the Word’s being with God from “the beginning” must here refer to the beginning of Jehovah’s creative works. This is confirmed by other texts identifying Jesus as “the firstborn of all creation,” “the beginning of the creation by God.” (Col 1:15; Re 1:1; 3:14) Thus the Scriptures identify the Word (Jesus in his prehuman existence) as God’s first creation, his firstborn Son. That Jehovah was truly the Father or Life-Giver to this firstborn Son and, hence, that this Son was actually a creature of God is evident from Jesus’ own statements. He pointed to God as the Source of his life, saying, “I live because of the Father.” According to the context, this meant that his life resulted from or was caused by his Father, even as the gaining of life by dying men would result from their faith in Jesus’ ransom sacrifice.—Joh 6:56, 57.