I think that is an excellent summary, UDS, but I would make two comments: one with respect to the reliability of John based on relative antiquity, and the other with respect to the usage by John of the terms Jew and Jewish.
Although I understand the rationale behind assigning greater credence to historical naratives on the basis of how contemporary they are, I submit that there are other factors, no less important, that ought to be considered in determining a narative’s historical accuracy and reliablity. Sure, it is true that, in general, if a work is excessively noncontemporary, there might be reason to doubt its veracity, or at the very least, its purity from hearsay. However, it is important to understand that one may not simply declare a work to be historically accurate merely because it is contemporary, nor may one declare a work to be dubious merely because it is not. As a matter of fact, if a narative is too contemporary, it might be suspect for that reason alone. Consider contemporary news reports about 9/11, the assassination of John Kennedy, and numerous other historical events of the modern communications age. Innacurate speculation often predominates initial reports, and it can be years before wheat and chaffe are separated, and even then, revisions can surface that are themselves based on less reliable early reports. Consider, for example, the grassy knoll and conspiracy theories permeating the culture even 40 years after Kennedy’s death. And this in an age when cameras place us live at events as they unfold. For a generation used to being immersed in instant news, it is easy to project the modern zeitgeist onto the ancient world. But that is a mistake. Owing to the very dearth of communications means in the first century, the fact that anything survived at all about Jesus’ life in puny Judaea is in itself remarkable. News and history were just as important to people at that time (although with a very different approach — less linear, more cultural) as they are today. Precisely because the populace was so illiterate, people who maintained histories were very highly regarded. There was no more important a community ritual than the telling of stories by visiting outsiders. People took time from their busy days to gather and listen to their reports. And just as certain people today have mastered specialized memory techniques, so did people then — except that the skill for people then was much more of a pressing need. Those responsible for passing history down through the generations were carefully chosen and demonstrated remarkable skills. If we compare an age where communication was both important and problematic with an age where we are postively saturated with a veritable Babel of communication, we are making a mistake. But aside from the matter of contemporanaeity, there are other, and equally significant, criteria for reliability — such as culture, prejudice, motive, context, and reputation.
Another mistake of zeitgeist overlay has to do with imposing modern usage of the term Jewish onto usage of the term in the first century, particularly with respect to the Gospels. Saying at that time that the Jews did this or the Jews did that had none of the racial and ethnic overtones that usage of the term has today. It was a political and religious reference, not a racial one. In Judaea, there were primarily Jews, Samaritans, Idumeans, and pagans, which consisted of Greeks, Romans, a few Egyptians, and a hodge-podge of other polytheists. Any references by John to a Jewish crowd or gang were meant to signify people who were sympathetic politically and religiously with the Sadducees or Pharisees (especially the Pharisees), the two primary Judaean political forces. Obviously, since Jesus Himself and practically all His disciples were Jewish, John did not intend to disparage all Jews as a race or culture. In fact, the usage of the term is so different today that the references ought to be translated differently. John was not an antisemite, and his references to Jews were not antisemitic. There is no need to tiptoe around them or attempt to excuse them. There is only the need to eradicate the ignorance surrounding them.