What exactly is Mary's "association" with, or "lesser duty or responsibility" towards my personal salvation? Though I have never prayed to her once in my entire life, does Mary know all about me, my sins, and my relationship with God? Finally, how does Mary as co-redemptrix "fit" scripturally? I'm sorry that I missed your earlier explanation. The only one that I can (sort of) remember from anyone is something like that since Mary suffered it makes perfect sense that she is the co-redemptrix. Obviously, the Bible makes no such assertion.
Catholics honour Mary, the Mother of Jesus. Mary is important because she points to Jesus and is the way God chose to come to us in Jesus. Indeed God made her ready to be Mother of his Son by making her uniquely free from the stain of Original Sin (the immaculate conception). Jesus is fully God and fully divine. This wonderful mystery comes about because God is the father of Jesus and Mary is his mother. Because Mary is his mother, Jesus is fully one of us, he is fully human. He takes to himself, through Mary, the fullness of our humanity so that all that is human may be redeemed. In Mary we see God loving us by choosing to come to us through a simple, young, poor woman.
Mary is also a model for how Christians act. She says “yes” to God and because of this, God does wonderful things through her. Mary doesn’t appear very much in the New Testament, but every time she does appear it is at a vital moment. She is there accepting the frightening message of the angel. (Lk 1: 26-38) She is there proclaiming God’s power in turning upside down the order of the world “putting down the mighty and raising up the humble”. (Lk 1:46-55) She is there at the wedding feast of Cana and right at the start of the ministry of Jesus she tells the servants at the wedding, and us, “do whatever he (Jesus) tells you. (Jn 2:1-12)She is there during the ministry of Jesus, and there we hear Jesus refusing to say “Blessed is the womb that bore you and the breasts that suckled you” but saying “Blessed are those who hear the Word of God and keep it” (Lk 11:27) or “My mother and brothers they are those who hear the word of God and act upon it” (Lk 8:21) – and that surely describes Mary. She is there at the cross, suffering with her Son (Jn 19:25-27). She is there after the resurrection, praying with the apostles (Acts 1:14)
There is danger of making Mary into a model of a submissive woman. In fact she is a strong woman: a woman who can face pain and suffering, a woman who can face social disgrace, a woman who can be a refugee. We see a woman who has the courage to hear the word of God and act upon it. A woman with the wisdom to say to the angel “I am the handmaid of the Lord, let it be to me according to what you say” (Lk 2:38) The strength to accept God’s will is strength indeed. Mary is not just a theological principle, Not just a model of how we should behave, she is a person we relate to. We come to her as a mother who loves us. At the foot of the Cross there is a wonderful moment when Jesus says to his disciple John “Behold your Mother” and to Mary “Behold your Son”. (Jn 19:27) Catholics have always found ourselves in this exchange. We, the followers of Jesus, have Mary as our mother, and Mary has us as her children. And it is in this personal relationship that we ask Mary, our Mother to help us. We’re not making her equal to God, but we’re asking her to pray for us, just as we might ask any trusted friend to help us.
http://www.life4seekers.co.uk/FAQ-RoleofMary.htm