The Savior and Keeper

Why is this called a Psalm of degrees? Can you 'get' salvation? Do we need some help or are we helpless as a dead body in the graveyard? What is the Source of our saving and keeping? Did every person die in the Garden of Eden? Is every single part of salvation attributed to Christ? Can we share in the glory of salvation? Why is it that everything that man does is temporary and destined to fail? Does the LORD keep us from evil?