Clasping the hands in Salah

Q 1: It is mentioned in the book entitled "Al-Mudawwanah Al-Kubrah" by Imam Malik (may Allah be merciful to him) (Vol. 1, Chapter on placing one hand over the other) that Malik was asked about placing the right hand over the left one during Salah (Prayer), and he answered: "I do not know this (to be done) in the obligatory Salah, (Part No. 6; Page No. 367) but I know that in Nawafil (supererogatory prayers). When a person stands for a long time, he may do so to support himself ." Does this mean that he does not like to place the right hand on the left hand during the obligatory Salah?If it is said: "It is confirmed in the Sunnah to place the right hand on the left one," I would say: "Yes, this was confirmed by the narration of Malik in Al-Muwatta', so how could he say: "I do not know this while he is the one who related the Hadith in his Muwatta' and on his authority Al-Bukhari and Muslim transmitted the Hadith! Therefore, the meaning is: He does not prefer to act upon this Hadith. You know how vast is the knowledge of Malik, his adherence to the Sunnah, and the actions of the Companions. Does his saying abrogate the Hadith; taking into consideration that I have read some books of Usul-ul-Fiqh (principles of Islamic Jurisprudence) and Hadith and I am comforted by the (Islamic) fundamental which Malik followed that the consensus of the people of Al-Madinah abrogates the Hadith if there is none of the Tabi`un (Followers, the generation after the Companions of the Prophet) who objects to this abrogation in any other country. If it is said: The saying of Malik: "I do not know" does not indicate the consensus of the People of Al-Madinah, I would say that this is not true because if there was any disagreement in this concern, he would have known about it and if he had known about it, he would have mentioned it. However, if there was no disagreement, this would indicate that it is an agreed-upon matter. If it is said that he did not know a Hadith in this regard, and then when he knew it, he mentioned it in Al-Muwatta', this would be refutable by his saying: "But if a person stands long in Nawafil..." This indicates that Malik was acquainted with the Hadith but he interpreted the ruling (only) on Nawafil and not the obligatory Salahs like the issue of those who eat and drink forgetfully in Ramadan according to Imam Malik. There is another answer which is: He related the Hadith so that people would not think that he had acted contradictorily to the Hadith or that he did not know the Hadith. He knew the Hadith but did not act according to it. Another answer is: When the narrator narrates the Hadith, (Part No. 6; Page No. 368) it does not indicate the abrogation of the Hadith even if it is sound. Another answer is: Ibn Al-Qasim used to be one of the followers of Imam Malik who memorized the Muwatta'. If the Hadith was not abrogated, he would have refuted the saying of Imam Malik.