I agree, mostly. But Christ did not need salvation.
I dunno... what about this:
Act 2:22 Ye men of Israel, hear these words; Jesus of Nazareth, a man approved of God among you by miracles and wonders and signs, which God did by him in the midst of you, as ye yourselves also know:
23 Him, being delivered by the determinate counsel and foreknowledge of God, ye have taken, and by wicked hands have crucified and slain:
24 Whom God hath raised up, having loosed the pains of death: because it was not possible that he should be holden of it.
25 For David speaketh concerning him, I foresaw the Lord always before my face, for he is on my right hand, that I should not be moved:
26 Therefore did my heart rejoice, and my tongue was glad; moreover also my flesh shall rest in hope:
27 Because thou wilt not leave my soul in hell, neither wilt thou suffer thine Holy One to see corruption.
28 Thou hast made known to me the ways of life; thou shalt make me full of joy with thy countenance.
29 Men [and] brethren, let me freely speak unto you of the patriarch David, that he is both dead and buried, and his sepulchre is with us unto this day.
30 Therefore being a prophet, and knowing that God had sworn with an oath to him, that of the fruit of his loins, according to the flesh, he would raise up Christ to sit on his throne;
He was not born with sin or sin nature. He did however fulfill the law as you said. Paul says we are to establish the law, so certainly we are to follow most of it. There are certain parts that are no longer necessary like tithing, and animal sacrifice.
I would agree. I think the only "law" we are to follow is the "law of love".
Now about Mat 5:18, Christ was correct that the law was in full force until it was fulfilled, and fortunately for us, Christ fulfilled the law. Romans 8:4 is a perfect fit with Rev 2:9 and Rom 2:29 they both refer to those who write the law of God on their heart and not as an outward show. Man will always struggle with this concept; you must change your heart.
Read Romans 6-8, my friend. The Law is still in full force. In fact, it is by The Law that we have the righteousness of Faith. The concept of Righteousness by Faith comes from The Law - Genesis 15.
Gen 15:5 And he brought him forth abroad, and said, Look now toward heaven, and tell the stars, if thou be able to number them: and he said unto him, So shall thy seed be.
6 And he believed in the LORD; and he counted it to him for righteousness.
But recall what Galatians 3:16 said -- that "seed" refers to Jesus Christ. Paul makes it pretty clear that God preached the gospel of Jesus Christ to Abraham, and it was this belief (in Jesus Christ) that was counted as righteousness.
Gal 3:8 And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, [saying], In thee shall all nations be blessed.
9 So then they which be of faith are blessed with faithful Abraham.
Romans 4 also confirms this.
According to Romans 8:4, when we die The Law is fulfilled. Christ fulfilled The Law by not sinning. We fulfill the law by paying the penalty for our sin (which is death). According to Romans 8:3, our sin is "condemned" in our flesh, while our spirit is made alive in Christ.
One thing I love about Paul is he had a billiant legal mind. He continually uses the Old Testament (The Law) to prove the covenant of faith in Jesus Christ. In Romans 7 Paul starts the chapter by demonstrating that - according to The Law, a woman who has a husband is free from the law binding her to her husband when the husband dies. He goes on to argue that - in the same way, we are free from The Law of sin and death because sin is condemned to our bodies, and we become free from The Law (the law is fulfilled) when our bodies die. However, we remain alive because our spirits are alive in Christ. So like the widow is free from The Law when her husband dies, so we too are free from The Law of sin and death.
Finally, I would remind you:
Rom 11:16 For if the firstfruit [be] holy, the lump [is] also [holy]: and if the root [be] holy, so [are] the branches.
17 And if some of the branches be broken off, and thou, being a wild olive tree, wert graffed in among them, and with them partakest of the root and fatness of the olive tree;
18 Boast not against the branches. But if thou boast, thou bearest not the root, but the root thee.
Do not dismiss the Jew or The Law. These being the natural branches and the root of Christianity. They are necessary for what Christ did to mean anything. The Law proves that salvation is by faith alone. Romans 9-11 talks about The Law having to conclude all under sin, thus proving that only the righteousness of faith can save anyone.