Alan,
:: The "Ransom Sacrifice" is one of the most perverse, incoherant and twisted religious ideas humankind has ever thought of. I have yet to find a Christian who can answer the above problems logically. Some find ways to skirt the issues, to be sure, but I'm talking about a logical presentation that answers all of the questions, as well as a number of others that also arise. Good luck if anyone wants to tackle it.
I believe my own version of Christianity is already considered perverse, incoherent and twisted, so I might be just the one to tackle this issue.
Sacrifices had two types of value in the context of Jewish and pagan religions that emphasized blood sacrifice:
1) The first ransom idea at the time was simply that something is sacrificed and the value of that thing will buy some kind of appeasement or propitiation from the God(s). A sheep or goat might appease a family's sins for a year. A couple of birds might appease a persons temporary sin (uncleanness) for something relatively minor. A bunch of bulls might appease a whole nation's uncleanness (Hezekiah). So the simplest idea was that the more valuable the sacrifice, the more valuable the scope of the atonement.
2) The blood and the specifics of several of the sacrifices had developed other meanings too. Animals already represented people vicariously, and priests represented the whole nation of people vicariously. The latter idea was convenient and practical because the priests who ate of the sacrifice actually ate vicariously for the whole nation. Otherwise, there would not be enough meat to go around, and this way, too, the Levites would all make a decent living even though almost all of them had the same job: kosher butchers. So another purchasing value of the sacrifice is that it meant that the whole nation would eat. In some sense this represented the "fertility" of the nation which explains "first-born" animals, "first-fruits" of grain, etc, and the biggest sacrifices were, of course, at planting time and harvest time.
Now on the value of the sacrifice of Jesus, John's gospel had deified Jesus from the opening verse, so by the time he gets to: "for God so loved the world that he gave his only-begotten Son..." the meaning of ransom in part 1 above is obvious. The better the sacrifice the bigger the atonment. A sacrificed god (John 1:1) ought to propitiate for entire world.
The other meanings and value that had been attached to idea of the sacrifice was that by participating in the sacrifice you were buying your livelihood, paying a small ransom as a bet against the whims of the gods. Storms and droughts and locust plagues were possible, but your harvest would still come in, your family would be fed, if you placed the bet against God's anger. You were purchasing a blessing from the gods, at least for the next season. This idea wasn't lost on the Gospels either. The eating and drinking of Jesus body and blood by anyone (who all are priests now) provides eternal life for all seasons.
Of course, most Christians want to make sense of Paul's comments about one man Adam and one man Jesus corresponding somehow. That's where most of the trouble comes from. Otherwise we can find enough answers in any Jewish, Mithraic, or other sacrifice-oriented religion.
Of course, I don't think a Christian has to make much of the sacrifice theory, because Jesus did not live up to these deified expectations of John or others. In a sense, however, his sacfrice was quite valuable in that it leaves us on our own again. We are left to wonder whether God has forsaken us, as Jesus did. We are on our own. We must find new lessons that learn from the false hopes and mistakes of Jesus followers (imo).
The closest thing to a practical ransom that Jesus might have actually provided was to delay the violent takeover of Jerusalem/Judea/Palestine by Rome. As the Sadducees commented: it is better for one man to die than for Rome to come and take away our [Temple and] nation. Ironically, even that ransom didn't work very well. (I'm talking about the literal story here, not whether such a plot by the priests ever really happened.) His followers made a martyr out of him and the Christians (in the story) were able to indict the highest levels of Rome (Paul v. Caesar) and the highest levels of the Jerusalem Temple cult (Sadducees Annas, Caiphus, etc.). Christians were partially vindicated, but when that vindication evolved into vindictive hopes against Rome (e.g., Revelation), those hopes failed. But love never failed.
In my own thinking, there was no real ransom, per se, but there was a great value to his sacrifice in that Jesus is described as knowing what the plotters were up to yet he had a message that was so important he realized that it was worth more than his life, so he still declared as openly as possible. He knew the danger to himself, his reputation, but he managed to find a way that declared the message from the rooftops, to a maximum number of people whom he was sure needed to hear it. Even though he encouraged others to have the same kind of love for others that would risk their own life if necessary to serve others, yet it worked out that he alone took the punishment.
How'd I do?
Gamaliel