So then, do you believe that everyone is already saved?
No, we are born sinful and in need of a Savior; each one of us. God gives us the gift of faith in order to trust in the Gospel message (the good news that because of Christ's death on the cross, we are forgiven). Without faith, we are dead in our sins.
Or is it only those who are Baptised who are saved?
Scriptures tell us that baptism saves, but that it's not the lack of baptism that damns us. Faith comes from baptism but it also comes by hearing God's Word. Those who hear about the good news, surely would want baptism!
What do Lutherans see salvation as meaning? Saved from what or to what? What saves people? Who is saved and how do they get that way?
Salvation means that God saves us from what we deserve, eternal punishment. How does God do this? First off, He gave the promise of a Savior in the book of Genesis and those who had faith (a trust) in that promise were saved. Jesus came and died on the cross in our substitute, for he was the perfect lamb. Baptism gives us the benefits earned at the cross, such as the washing away of our sins and clothing ourselves in Christ's righteousness.
God is the one who saves. Only HE can save us and He is the one who does that work; 100%. We cannot contributure to our salvation one iota. God uses means to bring us to salvation. Some of those means are of course, His Son and the cross, but also He uses man to spread the Gospel, He uses His Word to bring people to faith, He uses the Holy Spirit, He uses water combined with His Word in baptism, He uses His Word with bread and wine to keep us in faith, all these things God uses to show us His love for us and His salvation.
There is not one person who can contribute to his salvation by deciding, choosing, accepting, surrendering, etc..., for that would make salvation a work and we know that scriptures say that it's not by works. Faith is not a work because scriptures tell us it's a gift from God.
Those who have faith will be saved. But man can and does reject and those who do deserve eternal punishment. Those who reject, reject Christ and the cross and deny the forgiveness of sins. We are all justified by the cross, but those who reject also reject that justification and throw it back at God; not wanting it.
We don't know exactly who has faith and who is just a hypocrite. We can't see into people's hearts so we listen to their confession of what they believe or don't believe.
Hope that helps.