The three accounts of the conversion of Saul

We find three accounts of the conversion of Saul in Acts. The first one was part of a narrative as the story develops. The second one was Paul's defence before a mob in front of the Temple. The last one was Paul's defence before King Agrippa when Paul was on his way to Rome to appeal to Caesar. In two occasions St. Paul described his conversion experience. However, there are some differences which are difficult to harmonize. Why did Luke not harmonize them before presenting them to the readers? Let's us take a look at the table below to see their differences.

Acts 9:3-8	Acts 22:6-11 (to the mob before the Temple)	Acts 26:13-18 (Before King Agrippa)
Now as he journeyed he approached Damascus, and suddenly a light from heaven flashed about him.	As I made my journey and drew near to Damascus, about noon a great light from heaven suddenly shone about me.	At midday, O king, I saw on the way a light from heaven, brighter than the sun, shining round me and those who journeyed with me.
And he fell to the ground and heard a voice saying to him, "Saul, Saul, why do you persecute me?"	And I fell to the ground and heard a voice saying to me,'Saul, Saul, why do you persecute me?'	And when we had all fallen to the ground, I heard a voice saying to me in the Hebrew language,'Saul, Saul, why do you persecute me? It hurts you to kick against the goads.'
And he said, "Who are you, Lord?" And he said, "I am Jesus, whom you are persecuting;	And I answered,'Who are you, Lord?' And he said to me,'I am Jesus of Nazareth whom you are persecuting.'	And I said,'Who are you, Lord?' And the Lord said, 'I am Jesus whom you are persecuting.
but rise and enter the city, and you will be told what you are to do."	And I said,'What shall I do, Lord?' And the Lord said to me,'Rise, and go into Damascus, and there you will be told all that is appointed for you to do.' (22:10)	But rise and stand upon your feet; for I have appeared to you for this purpose, to appoint you to serve and bear witness to the things in which you have seen me and to those in which I will appear to you, delivering you from the people and from the Gentiles -- to whom I send you to open their eyes, that they may turn from darkness to light and from the power of Satan to God, that they may receive forgiveness of sins and a place among those who are sanctified by faith in me.'
The men who were traveling with him stood speechless, hearing the voice but seeing no one.	Now those who were with me saw the light but did not hear the voice of the one who was speaking to me. (22:9)
Saul arose from the ground; and when his eyes were opened, he could see nothing; so they led him by the hand and brought him into Damascus.	And when I could not see because of the brightness of that light, I was led by the hand by those who were with me, and came into Damascus.

Let us take Acts 9, Luke's account, as a reference. But don't forget, Luke obtained the information from Paul. Therefore, all three accounts came from Paul. Luke was only responsible for reporting these three different occasions. But why did Luke give three slightly different accounts? Did Luke report verbatim? If he did, why did Paul tell different things to different people? Did Paul tell the story in such a way as to adapt to his audience?
In the first verse, the basic facts were established. Saul was on his way to Damascus. A bright light shone about him. From the second and third accounts, we know that it was about noon. In the third account, the light enveloped the whole party, not just Saul. Why? What difference did it make to King Agrippa to include the whole party of persecutors?
In the second verse, Saul fell on the ground and he heard a voice saying 'Saul, Saul, why do you persecute me?'. However, in the third account, we know that the voice spoke in Hebrew. Moreover, an extra piece of detail was added "It hurts you to kick against the goads." This is probably a Jewish idiom. Again, why did Paul add this idiom for King Agrippa? Was he suggesting that King Agrippa was fighting against God if he meddled with the gospel Paul preached?
In the third verse, Jesus' answer was reported. In the second account, an extra piece of detail 'Jesus of Nazareth' was added for the mob. Why? Did the mob of Jerusalem not know that Jesus came from Nazareth?
In the fourth verse, Jesus continued his instruction, telling Saul to rise from the ground and enter Damascus. There he would be told what to do. In the second account, Saul asked what he had to do. The third account was more elaborate. In front of King Agrippa, Paul explained the mission God had commissioned him and God's promise to protect him. Did Paul want to convert King Agrippa as well?
The next verse is contradictory. In the first account, the accompanying party heard the conversion between Jesus and Saul. But in the second account in front of the mob, the accompanying party saw only the light but did not hear the exchange between Jesus and Saul. So, did they hear or did they not hear? Why didn't Luke harmonize the two accounts? Was it an oversight on Luke's part? Can anybody enlighten me on this?

Dear Jesus, tomorrow I will discuss with Deacon Tsang to clarify my vocation. Do You really call me to serve You as a Perpetual Deacon? Do I crave power and honour instead of serving You and the needy? Enlighten me, Lord, for I have been blind for too long. Amen.