The idea that someone else could sacrifice for anyone else's sins appears nowhere in Judaism (same with the concept of forgiving someone for their sins against a 3rd party - I'm often asked why Jews can't forgive the Nazis for murdering other Jews...its impossible, even G-d Himself cannot forgive for wrongs not done to Him, so how could I do it?).
As for defeating Satan (who's not a fallen angel, not some red guy with hoofs, horns and a pointy tail, not a rival of any kind, but rather a tempter of Man at G-d's behest and command - "ha satan" - the satan, not "Satan" as in a proper name) - that's up to each of us to defeat our own personal Evil Inclination. No one can do it for us, that's our own burden to fulfill by deeds.
There's also no concept, no hint of any kind, of a Messiah needing a do-over to complete his job - and there's no way that the Jesus of your faith (or anyone else, for that matter) ever completed the job. BTW, Jesus was rejected by the vast majority of the Jewish People of the time because they recognized that Jesus didn't measure up to the status of Moschiach (however good Jesus may have been).
Please read the links I gave you - Jesus was Jewish and from Bethlelem (Beit Lechem, actually), but that's about all. Its too general, too many people (including King David) meet those broad criteria. Moschiach ben David (the Messiah descended from David) will not be killed by anyone, period. Moschiah ben Yosef (descended from Joseph) will be a warrior who will (or may, depending on one's point of view) die while fighting the real-world enemies of Israel. Jesus qualifies as a candidate for neither position.
Again, I don't seek to insult you in any way, especially as you seem to be such a moral person, but your understanding of things Jewish seems to be somewhat less than complete.
You also state that we are to overcome our own sin with our deeds. A “works” theology. I have a question for you. How do you know if you have been good enough? Is there a time in your life that God comes and tells you the hour of your death and lets you know how many good deeds you must perform to enter the kingdom before you expire? That would be inconsistent with a loving God and not one that I would think many would want to follow. (But unfortunately do) I do not follow Jesus just so I can get a “get out of Hell free card”, if that’s what you might be inclined to think, rather I realize the depravity of my heart and come to Him for forgiveness and grace as no amount of good deeds could outweigh my sin. It is not a matter of (i.e.) 10 good deeds vs. 9 bad. It is that even one small sin declares me blemished and no unclean thing will EVER be able to enter the Kingdom of God. Sin like a cancer grows and it can never be permitted in heaven. God allowed us to experience freewill this go around and only those that chose Him and His Son and whose sin has been atoned will enter.
I will read your links if in turn you read mine. God Bless!
God governs our universe and has seen fit to offer us a pardon. †