Salvation for us is multifaceted and holistic. I agree with your Orthodox friend who points out that it means healing. The means of healing is Jesus Christ Himself, who assumed our flesh, took on our weaknesses and entered into death for us and thereby conquering it so that it does not rule over us. In this sense then, Jesus is our only Savior, and salvation can only come through Him. Now, here we must flesh out this process fully to understand it as did the Apostles and their successors in the Church. The salvation of Jesus Christ is given to us as a life in Him. It is being united to him in soul, body, and spirit. If we live in Him and He in us, this is salvation. Salvation is not a change in our legal status from guilty to not guilty before God. God loves us and does not change his attitude toward us ever.
Therefore if salvation is a life lived in and with Christ, the scripture tells us exactly how this is effected- through the Church. Salvation is a corporate reality as St. Paul describes it-we are one body. We partake of the life of Jesus as we partake of the mysteries of the Church- in Baptism, in Holy Communion, in confession etc. John Chapter 6 tells us how crucial the communion of the body and blood of Christ is- this is His life given to us. So we see in the body of Christ that we share this common life in Christ- which is salvation. Therefore we each can participate in others' salvation as we pray for each other and guide each other and commune with each other as part of the same body. If we look at the scripture- this is clear in the Apostle's thought. St. Paul says 16 Take heed to yourself and to the doctrine. Continue in them, for in doing this you will save both yourself and those who hear you.(1Ti 4:16-1 NKJ) St. James says the same: 19 Brethren, if anyone among you wanders from the truth, and someone turns him back, 20 let him know that he who turns a sinner from the error of his way will save a soul from death and cover a multitude of sins. (Jam 5:19-20 NKJ)
So we see that salvation as the life in Christ that He has given to us is effected through the corporate reality of the Church. We save each other, because we are all participating in the salvation that comes from Christ. Within that body we have those who are living, we have the angels, and we have those who have gone before us. We have those who the Church has declared to be Saints-the righteous who have been made perfect. St. Paul makes all of this clear in Hebrews: 22 But you have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, to an innumerable company of angels, 23 to the general assembly and church of the firstborn who are registered in heaven, to God the Judge of all, to the spirits of just men made perfect,24 to Jesus the Mediator of the new covenant, and to the blood of sprinkling that speaks better things than that of Abel. (Heb 12:20-29 NKJ) The Saints, then are alive and very much a part of the prayers of the Church. Indeed their prayers are powerful for it is the prayer of the righteous that is particularly powerful (James 5:16) We can see this clearly in the following verse from the book of Revelation: 8 Now when He had taken the scroll, the four living creatures and the twenty-four elders fell down before the Lamb, each having a harp, and golden bowls full of incense, which are the prayers of the saints. 9 And they sang a new song, saying: "You are worthy to take the scroll, And to open its seals; For You were slain, And have redeemed us to God by Your blood Out of every tribe and tongue and people and nation,10 And have made us kings and priests to our God; And we shall reign on the earth." (Rev 5:8-10 NKJ)
Of all of the Saints- the Holy Virgin is the most holy and most righteous, for, of all people who have ever lived, she was chosen to bring our salvation (Christ) into the world. He took His body from her (note-the body of Christ). She is the only one whom all generations will call blessed (Luke 1). She is the Mother of our Lord and therefore if we are Christ's brothers- she is also our Mother in the Church. There are no more powerful prayers that those of a mother who loves us. In this way we say that the Theotokos is the "salvation" of the Christian race.