What is the reason for specifically distinguishing and honoring Abraham (peace be upon him) with the attribute of being an intimate friend of God (al-Khullah)? And does God choose His prophets based on specific qualities or at random?

The actions of Allah Almighty are coupled with knowledge and wisdom. His choices, glorified be He, are not random, as He said: "And your Lord creates what He wills and chooses; none has the right to choose, but glory be to Allah and exalted be He above all that they associate with Him." This includes the selection of prophets, for He chooses none but those who are fit and worthy, in confirmation of His saying: "Allah knows best where to place His Message." And He chose our Prophet Muhammad, peace be upon him, from the best of mankind, as well as Abraham, peace be upon him, whom Allah chose due to His knowledge of his truthfulness, faithfulness, and obedience to Allah in all that He tested him with.