What is the authenticity of the hadiths narrated concerning the virtues of Surat Al-An'am? Is its recitation exclusively for fulfilling needs, facilitating marriage and childbirth, or for reciting over the deceased? Is there any evidence that reciting verse 124 of it is for fulfilling needs, or is this an innovation (bid'ah)?

There is no authentic hadith that proves a special virtue for Surat Al-An'am for fulfilling needs or facilitating marriage and childbirth. Nor do we know of any legitimacy for reciting it for the dying. The entire Qur'an can be used to supplicate and ask of Allah. If a verse of mercy is encountered, one can ask Allah with it, or supplicate to Allah with the prescribed supplications after recitation. Designating verses or surahs with virtues or for fulfilling needs without evidence is considered an innovation.