Is it permissible for someone afflicted by magic to recite the Quran over water themselves, and then bathe with it while dressed in their clothes, and to heat the water due to the cold weather?

It is permissible to recite the Quran over water for drinking and bathing, as the Prophet (peace be upon him) did by reciting the Mu'awwidhat (Surahs Al-Falaq and An-Nas) over himself. It is not a condition to be unclothed while bathing with water upon which ruqyah (Quranic recitation) has been performed or with any other water; what is important is that the water reaches the body, though covering oneself is preferable. There is no harm in heating water over which the Quran has been recited.