I would just disagree with the concept that the Talmud is a commentary on the Torah. It wasn't written as a commentary. Commentaries from those days were called psharim (singlar: pesher), and they gave elucidation on the meaning of texts, especially interpreted in light of the situation of the readers at the time. The midrash is much closer to the idea of pesher, especially texts such as Midrash Rabba and Midrash Tanchuma, which follow the order of the sidras as found in the Torah.
The Talmud is not a commentary on the Torah, though it certainly includes quotes from the Torah and from the rest of the Tanach. It is written as an elucidation not on the biblical text (which it uses as support for its arguments) but on Jewish life. The Talmud is a commentary on Judaism and how to understand the world through Judaism. It contains a lot of information that is relevant only within a given culture or worldview, so it disagrees at times with how we see the world through modern eyes - which is completely acceptable and to be expected of any book written in previous generations (even the Bible, in fact).
The kernel of the Talmud is the Mishnah, the oral law handed down by the Pharisees (Prushim) and those who followed them. The Mishnah set out to include the decisions of the major rabbis regarding six areas of Jewish law and custom. Each of these general topics is called a seder "order" (plural: sdarim), and it touches on many topics that are somehow related to the general order.
There are two talmuds (talmudim) - one from the Diaspora, called the "Babylonian Talmud"; and one from the Holy Land, called the "Palestinian (or, Jerusalem) Talmud". The most important of the two according to tradition is the Babylonian. The Talmud (Gmara) is a commentary on the Mishnah. Not all sections of the Mishnah contain a corresponding section of Gmara (such as Pirkei Avot, mentioned above), but all Gmara is written as a commentary on the Mishnah, even if it leads into discussions that are either only tangentially related to the Mishnah text or even not related at all.
So, what is the value of the Talmud to a Messianic Jew? For that question, you'd have to ask them. How can you personally benefit from reading the Talmud? First, take it with a grain of salt. There are a myriad of opinions expressed in the Talmud, and not all of them are "gospel truth", shall we say. Second, read it as a commentary of Judaism from the past. Its value for showing us how Judaism was in the early- and mid-First Millennium is incomprehensible. So, take it as a description of the past and learn from it. Read its social comments from the perspective of a historian, not a social critic. There are things written there that must be understood from within the culture, and don't forget that translation also alters some things - and that the Talmud is written in such a way as to make sense to the initiated while confounding those who are not yeshiva students.
Good luck in your reading, and don't forget to turn to people who know the Talmud when you have questions. Do not seek out anti-Talmud websites, because they often twist and distort what is written and make Jews into pedophiles, rapists, murderers and every other foul thing imaginable.
Regards,
YM
