Are the Seven Readings preserved from distortion or oblivion, and is it permissible for Muslims to rely on one reading and abandon the rest, and what is the ruling on the existence of anomalous readings?

The seven recitations (Qira'at Sab'ah) are continuously transmitted (mutawatir) and preserved. Their knowledge is a necessity of the religion (ma'lum min al-din bi al-darurah). It is not permissible for Muslims to restrict themselves to one recitation and abandon the others completely. Rather, it is a communal obligation (fard kifayah) that some of them learn these recitations, because preserving the Qur'an with the continuously transmitted recitations is a communal obligation upon the Ummah, as is teaching it, learning the recitations, and teaching them. As for the anomalous recitations (Qira'at Shadhdhah), it is not permissible to recite with them, but it is permissible to use them as evidence.