"Could you succinctly summarize the hermeneutical principle you/Ken Power are applying to know which laws are fulfilled in Christ, which are merely symbolic of higher principles, and which are still to be followed literally?"

I have no short answer to this question, don't even have a long answer because I still don't fully understand which are to be kept and which we don't need to, trying to understand which are for Natives (as sign bearers) and which are for Gentiles. I think people want a neat little package that says "literal, moral, civil, ritual, ceremonial, prophetic, spiritual, etc."

I'm afraid "succinct" answers are how we got into such a state of abysmal ignorance in the first place. Pidgeonholing mitzvot into neat little categories will lead you astray every time. That's why I wrote (and continue to work on) The Owner's Manual. As far as "hermeneutical principles" are concerned, they're based on something I found in both the Torah and the New Testament: God has apparently required us to do things He's made it impossible to do. (Shown up at the temple for Passover lately?) Since Yahweh is not a sadistic, micromanaging control freak, I have no option other than to look for symbolic meaning in the literal precepts. But it's not that the literal precepts have no value, you understand: we should refrain from eating pork, but the overarching principle is that we must be discerning about what we bring into our lives. We should honor our fathers and mothers, but the bigger issue is taking Yahweh and His Holy Spirit seriously. We should not commit adultery, but God is actually teaching us the larger principle of spiritual faithfulness---of not joining ourselves to false gods. The same thought process applies to virtually everything in the Torah: sacrifices, tabernacle architecture, civil, criminal, and cultural law, dietary precepts, cleanliness laws, agriculture, the calendar with its schedule of "appointments"---everything. Keeping the Torah's literal precepts won't save you (not that anyone has ever actually kept them all), but the Torah hasn't been replaced by grace: it has only been explained by grace.