What are the ("objective" not-context-sensitive) prescribed penalties for violation of each of the Ten Commandments?
The ultimate penalty is separation from a loving God for eternity. Remember, it is God who holds each one of us responsible for failing to live righteously.
(1) So, in your view, the Ten Commandments is the only law we need? (Y/N)
No, what I am suggesting is that the Ten Commandments are the basis for just laws. The principles behind just laws stem from them.
(2) And the only enforcement mechanism required is "separation from a loving god"? (Y/N)
No. That is the long term result. All kinds of situations in your life either draw you to God or away from Him. Some of those are pleasant and some are painful. My father's death in 1979 started me on a quest for meaning. The short term results are that you hear His word and what you do with it is between you and God. The short term result is that you reason about life and you either turn to God for answers or you turn to your own devices and human reasoning alone.
(3) Can we just fire all police officers and tell safety regulators they can retire? (Y/N)
No, they are there for a purpose. The world is full of many evils because people choose their ways instead of the way of God. Hence, we need restraints to lessen evil. We constantly see that we are incapable of living a completely just and good life outside of Jesus Christ. That is why the Good News is such an awesome realization. He became the substitute for those who truly put there trust and faith in Him. The OT sacrifice had to be offered time after time, year after year, to keep the covenant believers standing with God in good standing. Jesus' sacrifice and substitution was a one-time offering. That is all that was needed. Animal sacrifices pointed towards this greater sacrifice and were a substitute for the person and nation. The laying on of hands by the priest signified they identified with the sacrifice as should have been the sinner.
Hebrews 9 explains the concepts I am speaking of further,
7 but into the second, only the high priest enters once a year, not without taking blood, which he offers for himself and for the sins of the people committed in ignorance. 8 The Holy Spirit is signifying this, that the way into the holy place has not yet been disclosed while the outer tabernacle is still standing, 9 which is a symbol for the present time. Accordingly both gifts and sacrifices are offered which cannot make the worshiper perfect in conscience, 10 since they relate only to food and drink and various washings, regulations for the body imposed until a time of reformation.
Notice the reference to the outer tabernacle. It represented the OT order of worship or economy. Until that was
taken away, removed, it was binding. When did that happen? It happened in AD 70. The Romans destroyed the Second Temple in AD 70.
Remember, the blood represented life. Taking the blood meant death. The animal death should have been the death of the guilty party but God allowed an animal sacrifice (which was costly) as a covering until God Himself provided the ultimate sacrifice that would always meet the satisfaction of God. That animal was a provision God gave instead of the human life that sinned. That satisfaction would be a man since Adam brought sin into the world by his disobedience and separated humanity from that close relationship with God because of sin. The Son becomes a human being to accomplish what no other human could. A man must live a completely righteous life to put humanity back into the right relationship with God. Not only this, the man must pay the penalty for sin, which is death (spiritual separation from God), to satisfy God's justice. Sin must be met with.
He entered through the greater and more perfect tabernacle, not made with hands, that is to say, not of this creation; 12 and not through the blood of goats and calves, but through His own blood, He entered the holy place once for all, having obtained eternal redemption. 13 For if the blood of goats and bulls and the ashes of a heifer sprinkling those who have been defiled sanctify for the cleansing of the flesh, 14 how much more will the blood of Christ, who through the eternal Spirit offered Himself without blemish to God, cleanse your conscience from dead works to serve the living God?
15 For this reason He is the mediator of a new covenant, so that, since a death has taken place for the redemption of the transgressions that were committed under the first covenant, those who have been called may receive the promise of the eternal inheritance.
The New Covenant between man and God was made not by animal sacrifices to ratify it but by the blood of Jesus Christ!
16 For where a covenant is, there must of necessity be the death of the one who made it. 17 For a covenant is valid only when men are dead, for it is never in force while the one who made it lives. 18 Therefore even the first covenant was not inaugurated without blood.
The same principle is seen with a will. The will is only valid once the person who made it is dead.
24 For Christ did not enter a holy place made with hands, a mere copy of the true one, but into heaven itself, now to appear in the presence of God for us; 25 nor was it that He would offer Himself often, as the high priest enters the holy place year by year with blood that is not his own. 26 Otherwise, He would have needed to suffer often since the foundation of the world; but now once at the consummation of the ages He has been manifested to put away sin by the sacrifice of Himself. 27 And inasmuch as it is appointed for men to die once and after this comes judgment, 28 so Christ also, having been offered once to bear the sins of many, will appear a second time for salvation without reference to sin, to those who eagerly await Him.
He appeared in AD 70 for those eagerly awaiting Him to ratify the New Covenant and show those who doubted that He was who He said He was and that He had met God's righteous standards.
Matthew 26:59-64
59 Now the chief priests and the whole Council kept trying to obtain false testimony against Jesus, so that they might put Him to death. 60 They did not find any, even though many false witnesses came forward. But later on two came forward, 61 and said, “This man stated, ‘I am able to destroy the temple of God and to rebuild it in three days.’” 62 The high priest stood up and said to Him, “Do You not answer? What is it that these men are testifying against You?” 63 But Jesus kept silent. And the high priest said to Him, “I adjure You by the living God, that You tell us whether You are the Christ, the Son of God.” 64 Jesus *said to him, “You have said it yourself; nevertheless I tell you, hereafter you will see the Son of Man sitting at the right hand of Power, and coming on the clouds of heaven.”
The High Priest would understand that Jesus was who He claimed to be because Jesus would come in judgment forty years later (one generation) and they would understand Jesus was at His Father's side. If you understand the references to coming on clouds you would understand this is in reference to judgment. That judgment came in AD 70 and they would see, they would understand, what He said was true.
This version of "objective-morality" doesn't seem even slightly practical.
It gives the basis for morality. It necessarily comes from the unchanging, ultimate, absolute, objective, omniscient, eternal best - God. It presents principles that are witnessed in human laws throughout time. We understand that it is wrong to murder, steal, lie, and so on. That is implanted in most human minds (excepting those minds that are so corrupt and seared by self-deception) yet without God, there is nothing to compare good with since our minds and thinking are relative and subjective. Thus, we have the necessary standard only grant that God exists.