Does your soul have any power over what you do? Is your soul like your free will or conscience? If it is a different entity, could a person’s soul go to heaven without the rest of the body?

No—your soul does not have any power over you. It IS you! Our souls are not like our free will or our conscience. Our souls reflect the consequences of the choices we make with our free will and conscience. Our souls are the real us. When we die, we separate from our mortal bodies. God told Adam and Eve this would happen: To Adam he said, “Because you listened to your wife and ate from the tree about which I commanded you, ‘You must not eat of it,’ cursed is the ground because of you; through painful toil you will eat of it all the days of your life. It will produce thorns and thistles for you, and you will eat the plants of the field. By the sweat of your brow you will eat your food until you return to the ground, since from it you were taken; for dust you are and to dust you will return”—God speaking to Adam, Genesis 3:17-19. That consequence passed on to all the human race that has followed, as Paul wrote in his letter to the church at Rome: Therefore, just as sin entered the world through one man, and death through sin, and in this way death came to all men, because all sinned—Paul, Romans 5:12. Basically what is being told us through these verses is that we all experience death and, even before that final moment, we all experience aging. Aging is simply the foreshadowing of the death that is to come. When we die, we lose our mortal, temporary, human bodies. However, our souls, our very essence, continues on. Our bodies are mortal but our souls are immortal but, for us to exist in an immortal setting—eternity—we need a new kind of body, a body capable of lasting for eternity. Paul explains: So will it be with the resurrection of the dead. The body that is sown is perishable, it is raised imperishable; it is sown in dishonor, it is raised in glory; it is sown in weakness, it is raised in power; it is sown a natural body, it is raised a spiritual body. If there is a natural body, there is also a spiritual body—Paul, I Corinthians 15:42-44.
He goes on to say, And just as we have borne the likeness of the earthly man, so shall we bear the likeness of the man from heaven. I declare to you, brothers, that flesh and blood cannot inherit the kingdom of God, nor does the perishable inherit the imperishable. Listen, I tell you a mystery: We will not all sleep, but we will all be changed—in a flash, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, the dead will be raised imperishable, and we will be changed. For the perishable must clothe itself with the imperishable, and the mortal with immorality—Paul, I Corinthians 15:49-53. But the great delight in eternity, of course, is for the Christian that, even now, death will bring God’s children directly into His presence. The Old Testament previewed this with its picture of Sheol, the spiritual land of the dead which, though one place, contained two different areas—one for the righteous and one for the unrighteous, with two very different experiences awaiting them. For the righteous in the Old Testament, Isaiah told us that, Those who walk uprightly enter into peace; they find rest as they lie in death—Isaiah 57:2. Three hundred years before, David saw the end of earthly life as something to look forward to: And I—in righteousness I will see your face; when I awake, I will be satisfied with seeing your likeness—David, Psalm 17:15. Certainly Christ supported this picture of the afterlife with His story of the rich man and Lazarus (Luke 16:19-31). From that story, we see four very clear realities: (1) This dead man, now existing in Hades (NT, synonymous with Sheol in the OT) was fully conscious immediately after death; memory, speaking and pain were all a part of his experience; (2) this dead man’s eternal destiny was irrevocably, irreversibly fixed—no “do-overs”; (3) this dead man knew his afterlife was completely just and fair (he never complained about any “unfairness”); and (4) this dead man was not in “hell” but in “Hades.” Hades was, and is, the place for the unforgiven dead to be held while waiting for final judgment. With the coming of the New Testament, we see a shift, from having to wait to experience the presence of the Lord to its being an immediate reality following death. When Jesus was in His final moments on the cross, He made a special promise to the penitent thief being crucified at His side: One of the criminals who hung there hurled insults at him: “Aren’t you the Christ? Save yourself and us!” But the other criminal rebuked him. “Don’t you fear God,” he said, “since you are under the same sentence? We are punished justly, for we are getting what our deeds deserve. But this man has done nothing wrong.” Then he said, “Jesus, remember me when you come into your kingdom.” Jesus answered him, “I tell you the truth, today you will be with me in paradise”—Luke 23:39-43. And certainly Paul, himself very familiar with being near death, wrote to the church at Corinth: We are confident, I say, and willing rather to be absent from the body, and to be present with the Lord—Paul, II Corinthians 5:8 (KJV). He reiterated this in his letter to the church at Philippi, telling them, For to me, to live is Christ and to die is gain. If I am to go on living in the body, this will mean fruitful labor for me. Yet what shall I choose? I do not know! I am torn between the two: I desire to depart and be with Christ, which is better by far—Paul, Philippians 1:21-23. The assumption that has been made from this is that there are no longer two “areas” of Hades where the dead are being held—one for the righteous and one for the unrighteous. While the unrighteous dead remain in Hades, the righteous dead have been transported to the presence of God in heaven, which is why Paul can write about and look forward to his imminent arrival in heaven immediately after his life on earth is ended. The unrighteous wait for final judgment (the “Great White Throne” judgment)—and then? John tells us in the book of Revelation: Then I saw a great white throne and him who was seated on it. Earth and sky fled from his presence, and there was no place for them. And I saw the dead, great and small, standing before the throne, and books were opened. Another book was opened, which is the book of life. The dead were judged according to what they had done as recorded in the books. The sea gave up the dead that were in it, and death and Hades gave up the dead that were in them, and everyone was judged according to what they had done. Then death and Hades were thrown into the lake of fire. The lake of fire is the second death. If anyone’s name was not found written in the book of life, he was thrown into the lake of fire—Revelation 20:11-15. That’s why we talk about eternity being a matter not of duration but destination. In either place—heaven or hell—we will carry our souls in immortal bodies, which will fully experience our eternity in every way imaginable—physically, consciously, mentally, spiritually and emotionally. We will have never been more alive.