On the last item, at least, I think that a recent article by Mickey Klink (a professor at Biola University) helps out a lot. When Mary asks Jesus for help, his response is a rare phrase (ti emoi kai soi) that is actually a Hebrew idiom rather than normal Greek. My Greek students always struggle with translating it, because it looks like it should mean "what to me and to you?" Any good commentary will tell you that this phrase is used three or four times in the Septuagint (LXX, the Greek Old Testament) to mean something like "what do I have to do with you?" or "why are you bothering me with this?" Mickey Klink added an important observation: on one particular occasion in the OT, someone asked a prophet for a water-related miracle, and the prophet answered ti emoi kai soi, but then went ahead and performed the miracle.
In 2 Kings 3:9-23, the allied armies of Judah and Israel faced a crisis - they were out of water, and the Moabites were about to attack. They asked Elisha for help, but Elisha at first refused because the king of Israel still worshipped idols. However, he then gave instructions to prepare for the miracle - the army dug trenches and waited for water. When the trenches were miraculously filled the next day, the rising sun made them look red as blood. In Hebrew, both "red" and "blood" are terms occasionally used to describe wine.
So what is John doing with this story? By having Jesus refuse with the distinctive phrase ti emoi kai soi, but then complete the miracle, John is showing us that Jesus is much like the great heroic prophet Elisha - something John often does.
This adds to the overall sense of the wine miracle that it is all about Jesus. Jesus' words and actions show him to be as great as Elisha. By converting ceremonial water into celebratory wine, he shows that he is replacing the purity rituals of Judaism. Jesus' disciples see the miracle and they understood that its purpose was to "display his glory," and they grow in their belief in him (John 2:11).
The picture: Water to Wine, in Das Plenarium oder Ewangely Buoch, 1516. Courtesy of the Digital Image Archive, Pitts Theology Library, Candler School of Theology, Emory University.