If all he was claiming was that he lived before Abraham and not yet died, nor being equal with God, then I think the Jews would have merely laughed at him (as I am doing at this supposition) or found a nice rubber room for him.
Not being a proffesional exegete I can't comment on the greek grammar involved but for a nice concise summary of some of the arguments involved I refer you to Purpose and Meaning of "Ego Eimi" in the Gospel of John In Reference to the Deity of Christ . Here's a nice sampler of how the author nails those who deny the clear meaning due to faulty presuppositions.
It is not hard to understand why there have been many who have not wished to make the connection that John makes between Jesus and Yahweh. One cannot make this identification outside of a trinitarian understanding of the Gospel itself, as one can certainly not identify Jesus as the Father in John's Gospel, hence, if Jesus is identified as ego eimi in the sense of the Old Testament ani hu, then one is left with two persons sharing the one nature that is God, and this, when it encounters John's discussion of the Holy Spirit, becomes the basis of the doctrine of the Trinity! Indeed, many of the denials of the rather clear usage of ego eimi in John 8:24, 8:58, 13:19 and 18:5-6 find their origin in preconceived theologies 18 that are nearly unitarian, subordinationist, or so enamored with naturalistic rationalism as to be antisuper-natural. An interpreter who is unwilling to dismiss the words of Scripture as simply "tradition" (and hence non-authoritative) or to interpret Scripture in contradiction with itself (as in a violation of strict monotheism in the positing of a being who is quasi-god, mighty, but not "almighty") will be hard pressed to avoid the obvious conclusions of John's presentation. Lest one should find it hard to believe that John would identify the carpenter from Galilee as Yahweh Himself, it might be pointed out that he did just that in John 12:39-41 by quoting from Isaiah's temple vision of Yahweh in Isaiah 6 and then concluding by saying, "These things Isaiah said because he saw His glory and he spoke about Him." The only "Him" in the context is Jesus; hence, for John, Isaiah, when he saw Yahweh on His throne, was in reality seeing the Lord Jesus. John 1:18 says as much as well.
Not if they thought he was a demon.
Regarding John's assertion of Jesus' divinity, of all the Apostles, John is the only Apostle who leaves no doubt that Jesus is divine.
The whole issue with John came up when you asserted that cJesus was crucified because John wrote about him cliaming to be God. That would be only according to Mark.
But as much as the other Gospels speak of Christ's humanity, John's speaks of his divnity ("and the Word became flesh"). But think of the chronological aspects of these Gospels. John's is being written at the end of the first century, some 50-60 years after Chirst, after Jamnia, and when Christian theology is distinctly rejecting Judaism.
It took Christianity some 400 years to fully formulate what it believed in and to canonize the New Testament. To claim that it was equally believed everywhere by all is simply not the case, just as it is the case today. The same thing is true with Christ's divnity.