Welcome to you, TripleO,
I will sketch a few answers.
At the back of your mind though, please remember that Christ was the whole embodiment of the whole of God. As Redeemer, He was still the whole Word made Flesh as much as any other of His roles prophetically declaimed, or foreshadowed in the lives of Old Testament saints.
What exactly is redemption?
The act of buying back something which was yours, but which has fallen into the possession of another. Essentially, it's very unfair to the redeemer, but, he considers the thing worth reclaiming, whatever the cost.
Why is redemption needed?
I guess you might be able to work that out from the first answer.
How we can be redeemed?
In that Christ died for all mankind, the work of redemption has been completed on the cross by the Son, and accepted by the Father.
For by one offering he hath perfected for ever them that are sanctified.
Who redeems us?
These verses roll up all the necessary ingredients.
6 To the praise of the glory of his grace, wherein he hath made us accepted in the beloved.
7 [u]In whom we have redemption through his blood[/u], the forgiveness of sins, according to the riches of his grace;
8 Wherein he hath abounded toward us in all wisdom and prudence;
9 Having made known unto us the mystery of his will, according to his good pleasure which he hath purposed in himself:
10 That in the dispensation of the fulness of times he might gather together in one all things in Christ, both which are in heaven, and which are on earth; [i]even[/i] in him:
11 In whom also we have obtained an inheritance, being predestinated according to the purpose of him who worketh all things after the counsel of his own will:
12 That we should be to the praise of his glory, who first trusted in Christ.
1 Corinthians 1
29 That no flesh should glory in his presence.
30 But of him are ye [u]in Christ Jesus[/u], who of God is made unto us wisdom, and righteousness, and sanctification, [u]and redemption[/u]:
When can we be redeemed?
We come into the good of redemption by faith.
Paul defines what must be believed, in Romans 10:9 - That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.
What are we being redeemed from?
Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned:
12 Saying, I will declare thy name unto my brethren, in the midst of the church will I sing praise unto thee.
13 And again, I will put my trust in him.
And again, Behold I and the children which God hath given me.
14 Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil;
15 And deliver them who through fear of death were all their lifetime subject to bondage.
At the same time as destroying him that had the power of death, in whose grip we lay through Adam's sin, He put to death 'our old man' (Rom 6:6) that the body of sin might be destroyed, (This is our key to victory over sin.) and through faith, we are set apart (sanctified) unto Him.
I [i]am[/i] he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death.
Whether or not it is a one off thing or an ongoing process?
Very much a one-off.
I'd say that grasping this truth is fundamental to understanding the work of Christ, and that He fully intends to restore our souls (Psa 23:3) regardless of how long it might take to make us like Himself. Becoming His possession is a transaction swiftly made, but once.
The process of becoming like Him, is by looking at Him. We are changed from glory to glory through being able to see Him face to face, and live.
2 Corinthians 3:18
But we all, with open face beholding as in a glass the glory of the Lord, are changed into the same image from glory to glory, [i]even[/i] as by the Spirit of the Lord.
I prefer Tyndale's translation of this verse, which leaves out the mirror - or rather, we are the mirror:
[i]But we all behold the glory of the Lord with His face open, and are changed unto the same similitude, from glory to glory, even of the Spirit of the Lord.[/i]
Notice that we experience the effect of redemption as we abide in Christ. As we abide in Him, He comes to dwell in us. (John 14 - 17)
I hope these thoughts help you unravel what's on your mind.