What are the deeds and characteristics of those brought near (to Allah), and how can a Muslim become one of them? Can a repentant sinner join them even if they are not deeply versed in the Qur’an and faith, and what is the minimum number of individuals in the group?

The fact that a servant has sinned does not deprive him of the status of the 'foremost' (al-muqarraboon) if he repents to Allah, for the one who repents from sin is like one who has no sin. And "the foremost, the foremost" are those who were foremost in faith from every nation, or those who prayed towards the two Qiblas, or the people of the Qur'an, or the Prophets, or those who were foremost in going to mosques and going forth in the way of Allah. Their re-mentioning is for emphasis, or because those who are foremost in obeying Allah are foremost in His mercy. And "the foremost" (al-muqarraboon) are those who are with Allah in the shade of His Throne and in His proximity. Their number cannot be determined, and what is important is to act as they acted so as to join them.