As I noted in my previous post, the western medieval Bible was in Latin, having been translated from the Greek by Saint Jerome around the year 400 so that people in the western Roman Empire could more easily read it. This meant that, throughout the Middle Ages, Latin remained both the language of government (following the Roman model) and the language of religion.
It also meant that the Latin church and the Greek Orthodox church, which continued to read the Bible in Greek, decided that the other guys did not understand the Bible properly at all.
There never was a single "original" Bible from which all others were copied. The different sections, or books as they are called, presumably each had an original version when they were first written, but different congregations over time adopted slightly different collections of books and put them together slightly differently.
Add to this the fact that, a thousand years and more before the printing press, everything was hand-copied and thus never precisely alike, and it's easy to see why there was variation. This worried medieval people. Because the Bible was supposed to be God's word, they didn't think that a lot of variety was appropriate.
Around the year 800 Alcuin, the head of the school at Charlemagne's court, decided to prepare a definitive Bible. He and those working with him looked at all the oldest Bibles they could find, comparing them line by line, trying to determine when there was a variant which was the "real" reading. This is the approach modern scholars still take when trying to determine the original or most accurate version of a text.
Then Alcuin had the whole Bible carefully copied out in the "corrected" form, using a new, tidy type of handwriting, called Caroline miniscule. It looks a whole lot like modern printing, for the excellent reason that modern printing is based on it. Other churches around Charlemagne's empire were urged to come, look at the Alcuin Bible, and make careful copies of their own of this definitive text.
The Bible in the Middle Ages, like now, was an extremely popular book, with an enormous number of copies made. Because it is so long, it never existed in a single volume, but rather would be broken up into several volumes. A volume just of the Psalms, or just of the Gospels, was very common.
Anyone learning Latin (which had separated itself off from Old French, Old Italian, etc. by the ninth century) would do so in large part by studying the Bible. This meant that Jerome's vocabulary and syntax became the standard for medieval Latin. Churchmen essentially memorized large parts of the Bible. Monks would sing their way through the whole Psalter in a week or so, then start over. Biblical turns of phrase peppered their writings, not necessarily direct quotes but references to biblical ideas.
At the schools and developing universities, the Bible was a major source of study. No one read the Bible literally, or at least not just literally. There was far too much in it, from Jewish dietary laws to Jesus's suggestion that his followers needed to give up all their possessions and wander barefoot around the Sea of Galilee, that people who considered themselves good Christians did not adhere to.
Rather, the Bible was to be read at four levels, literally to start, then morally (seeing what sort of message was conveyed), allegorically (so that the love poems that make up the Song of Solomon were interpreted as meaning Christ's love for His church), and anagogically, the last meaning that the Old Testament prefigured the New, so that Abraham's sacrifice of Isaac was considered to refer to God's sacrifice of His only son.
Many, many people wrote Bible commentaries. In the twelfth century, "glossed" Bibles became common, where the Bible text was written in large letters in the center of the page, and commentary on each verse was written in the margins, or even between the lines, in a much smaller hand. Often there would be strips of commentary down the side, here is what Augustine had to say, here's what Jerome said, here's what Bede said, and so on. These glosses became fairly standardized, but again, no two volumes were exactly the same.