First point would be that Ya'aqob's letter does not fall into the criteria. It is nothing more then a letter written from one man to another, or others. Yah did not inspire, and Ya'aqob doesn't claim that Yah inspired it. It is not part of Yah's Word. It is nothing more then writings of a man.

Now second since that man happened to spend his whole life with Yahowsha, what he has to say may be worth reading, while not being considered Scripture. With that in mind I would note that we have no way of knowing rather or not Ya'aqob actually penned these words. The only portion of this "chapter" of his letter which are extant in the oldest manuscripts are "verse" 10, 11, 12, 18, 16, 17 & 18. So we have nothing of 26 or 27 from the first 4 centuries after it was written.

The Dead Sea Scrolls date to the 2nd and 3rd century BCE, Ya'aqob would not have wrote his letter until the mid to late 1st century CE. So there is no way for any of his letter to have been part of it. When it comes to the Greek text the earliest manuscripts we have date to the 1st, 2nd and 3rd century CE, the reason for the 3rd century CE cut off has to do with the way the text were transmitted after that point, many liberties were taken, and the rise of Constantine and his church. The verses listed are found in P23, parchment 23, which dates to late second century early third century.

Sarah,

According to Wikipedia:

The Dead Sea Scrolls are a collection of 972 texts discovered between 1946 and 1956 at Khirbet Qumran in the West Bank. They were found in caves about a mile inland from the northwest shore of the Dead Sea, from which they derive their name…..
The texts are written in Hebrew, Aramaic, Greek, and Nabataean, mostly on parchment but with some written on papyrus and bronze.[2] The manuscripts have been dated to various ranges between 408 BCE and 318 CE.

http://en.wikipedia.org/wiki/Dead_Sea_Scrolls

However, according to the following site there were some manuscripts found from the first century but they are “non-Biblical”.

Scroll dates range from the third century bce (mid–Second Temple period) to the first century of the Common Era, before the destruction of the Second Temple in 70 ce. While Hebrew is the most frequently used language in the Scrolls, about 15% were written in Aramaic and several in Greek. The Scrolls’ materials are made up mainly of parchment, although some are papyrus, and the text of one Scroll is engraved on copper….

Among the Scrolls are partial or complete copies of every book in the Hebrew Bible (except the book of Esther). About a dozen copies of some of these holy books were written in ancient paleo-Hebrew (the script of the First Temple era, not the standard script of the time)…

The Qumran Caves Scrolls preserve a large range of Jewish religious writings from the Second Temple period, including parabiblical texts, exegetical texts, hymns and prayers, wisdom texts, apocalyptic texts, calendrical texts, and others. Some of the works discovered among the Dead Sea Scrolls were known previously, having been preserved in translation since Second Temple times. The term "Pseudepigrapha" was used for these works, such as the book of Jubilees which was known in Ethiopic and Greek versions before being found in Hebrew in the Qumran caves. Many other non-biblical works were previously unknown.

http://www.deadseascroll...the-scrolls/introduction

BTW, you can look at photographs of some of the scrolls here:

http://www.deadseascrolls.org.il/

Shalom