Let me preface that I'm not trinitarian but I do have a soft spot for some of the "heterodox" ideas about Jesus <----- "hetero" to JWs and most other Protestant and Catholic groups, anyways.
Now, if Trinitarians just had that single matching "I AM" expression found at John 8:58 and Exodus 3:12-14, then all you put forward could make their position seem somewhat weaker.
But readers of John who were very familiar with the Septuagint would recall a few more matches to some interesting passages in Isaiah.
Like Isaiah 41:4 where Yahweh is clearly calling himself the first and the last and that "I am he", or another example would be the comparison found between what Yahweh says at Isaiah 43:10 and what Jesus is made to say at John 13:19.
Couple that Old Testament literature background to yet other ways John uses the "I AM" expression and then one can see how there can be a strong case made that John portrays a Jesus who is much more Divine than just a created angel. (like when Jesus says that he is the man the roman soldiers were looking for and everyone falls to the ground...He utters "I AM" and people bow down...like in obeisance)
Personally I think the earliest edition of John was heavily proto-gnostic.