Law and Gospel: Underlying Assumptions

There are certain truths relating to the Law that I am absolutely certain of, so I want to lay these out briefly, for my own good and also to dispell any notions that I might be wandering into any kind of works-righteousness territory. The Scripture references given are only a minute sample of abounding evidences for the following truths. You can tell I was mainly paging through Romans as I wrote this:

1. Keeping the Law is not the source of our righteousness. (Romans 3:20)

2. We are justified before God by grace alone by faith in the atoning sacrifice of Jesus on the cross. (Romans 3:22-25; Ephesians 2:8,9)

3. The Law serves to bring conviction of sin and show us our need for Christ's atoning sacrifice because it is impossible for any human (other than Jesus) to live up to its standards and carry it out perfectly. (Romans3:19,20; 5:20,21)

4. As a believer, I am no longer condemned by the law. (Romans 8:1,2)

5. God's grace does not excuse us from obedience, but rather motivates us toward greater obedience. (Romans 6)

I'm positive there are more things that I'm sure of, but they're not coming to me right now. Those are at least the basics. So my main questions concerning the law and it's relationship to the believer are things along the lines of how much of the Mosaic Law is relevant to gospel-motivated obedience in the Christian life. Obviously anything repeated and expanded by Christ in the gospel accounts or by any of the Spirit-inspired New Testament writers stands. But what about all the other commands of the law? Are they merely for anthropological enthusiasts, or should we regard them as ageless wisdom given by our omnipotent Creator? More thoughts later...