Question 1: If Jesus already died for our sins (past tense) and they’re already forgiven, why would need to confess sins (present tense)?

Answer: Some reject the idea that 1 John 1:9 could indicate a "present tense" or "right now" forgiveness since we were already forgiven 2,000 years ago. However, if you reject 1 John 1:9 as applying to believers on that basis, you really need to be prepared "reassign" to unbelievers other Scriptures as well that point to a "present tense" receiving of forgiveness.

When we talk about a believer receiving forgiveness, we're not saying that their forgiveness hasn't already been provided for. However, forgiveness is freshly received, realized, and applied when we appropriate our faith afresh and anew in the light of acknowledged sin.

James 5:15 says, ...And if he has committed sins, he will be forgiven. James did NOT say, “he was forgiven 2,000 years ago,” he said “he will be forgiven.” Legally, Jesus paid the penalty for his sins 2,000 years ago, but experientially, the person was receiving forgiveness at that time.

Second Corinthians 7:1 says, "Therefore, having these promises, beloved, let us cleanse ourselves from all filthiness of the flesh and spirit, perfecting holiness in the fear of God." Again, legally, the cleansing was procured 2,000 years ago. Experientially, we receive it and experience it as we yield to, cooperate with, and trust in God.

Peter’s admonition to Simon indicates that the receiving of forgiveness occurs in the present tense. Keep in mind that Acts 8:13 says, "Then Simon himself also believed; and when he was baptized...”

And when Simon saw that through the laying on of the apostles’ hands the Holy Spirit was given, he offered them money,  saying, “Give me this power also, that anyone on whom I lay hands may receive the Holy Spirit.”  But Peter said to him, “Your money perish with you, because you thought that the gift of God could be purchased with money!  You have neither part nor portion in this matter, for your heart is not right in the sight of God.  Repent therefore of this your wickedness, and pray God if perhaps the thought of your heart may be forgiven you. For I see that you are poisoned by bitterness and bound by iniquity.”
(Acts 8:18-23)

Peter did not tell Simon that he was already forgiven, but sternly admonished him to seek God in this matter.

The fact that grace has provided forgiveness does not mean that Christians have automatically received that forgiveness. I believe it's in this light that John said, "If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness" (1 John 1:9).

Legally, our sins were forgiveness 2,000 years ago. Experientially, we receive cleansing and forgiveness as needed by faith. This may also be why Hebrews 4:16 says, "Let us therefore come boldly to the throne of grace, that we may obtain mercy and find grace to help in time of need." The price for us to receive mercy was paid for 2,000 years ago. We receive that mercy experientially and progressively by faith.

To me, this is similar to a child being born into a family. He is 100% a child of his parents. He has their DNA, and everything about him is "family." When he's five years old, he may go out and fall in a mud puddle. That doesn't make him any less a child of his parents, but he does need a good bath to get the dirt off. 1 John 1:9 is that good bath, and I believe with all of my heart it does apply to Christians.