If Paul said anything of value then you should be able to find it in the Tanach anyway;
The Tanakh does not contain everything we need to know, the Rabbis are more than happy to admit this as well, so we turn to Commentaries and extracanonical literature. In Paul's case however, his Torah commentary seems to be more of an anti-Torah commentary.
but how do you intend to keep Torah?
What do you mean exactly? My main concern of how to keep Torah is how exactly some of the vague concepts apply. For instance, I've had a long struggle with the aspect of Kosher slaughter, whether or not that's what is meant by "As I have commanded you". I've come to accept it, while hungrily staring at otherwise fine quality Organic meat that I refuse to eat due to my acceptance of this. The issue of how to obey Torah properly is a central issue of whether we take Jesus's commentary or the Rabbis', or the Kairites, or any in between.
You have already become Jewish if you do that,
Wrong. One does not "become Jewish" by obeying the Torah in and of itself. The word "Jewish" in terms of religion, almost exclusively means "Rabbinicist" in modern speak, and the Rabbis have no serious monopoly on how to interpret Torah.
Now if you mean "become Jewish" culturally if not ethnically, I was born 100% Ashkenazi into a Reform Jewish Family that was very minimalist in Torah observance, but not as minimal as many others at least. So I never "became" Jewish. I've always been "Jewish". I find it interesting however that acceptance of one particular Rabbi's interpretations (who in reality doesn't really deviate much from Shammai) suddenly makes you "not Jewish" but not another.
With that said, the aspect of "Becoming Jewish" in all Rabbinical interpretations involves a formal conversion process. Unfortunately, the word "Jewish" in a religious sense has been monopolized to mean only those who follow specific interpretations of the text in terms of a Talmudic framework. With that said, I see no reason why one who obeys the Torah would "become Jewish", or why "becoming Jewish" is exclusive from following the teachings of Yeshu, of what we know from him, except by the decrees of the Talmudists.
and why would a Jewish person desire to study the NT other than for historical reasons?
Because they may be interested in the prospect that Yeshu was either the Messiah or had valid commentary on the Torah and may be interested in a Kairit-ish perspective on the Rabbinicists. According to what the Gospels say at least.
Why thank you.
What you say about Paul could be correct, but the thing I am not understanding is you. I don't see why you would torment yourself by living apart from other Jews.
I prefer what I consider to be what God wants over the Social network of what I consider to be an extension of what caused them to be punished by God. God's a much better friend than any social support network could be. I don't consider it too far different than what the Essene mindset was like. It's mostly a matter of Theological difference. But there's also a Social aspect I'm not going to mention here.
I cannot see you sitting through a typical sermon in a typical Church anywhere.
I have worked for churches and had to sit through the same sermons over and over. I couldn't stand it (particularly their interpretations and dogma and doctrine), but I was more than happy to help them part with some of their money.
The loner lifestyle is something I've learned to love, and that's exactly what I believe Yeshua intended. Besides, going against the tendency for social group think has its perks. Being close with God is way better, but that's another story.