1. Is it permissible to blow into one’s drink?

 No, it is not permissible It was narrated from Abu Sa’eed al-Khudri that the Prophet (ﷺ)  forbade blowing into one's drink. Narrated by al-Tirmidhi (1887) who said: a saheeh hasan hadeeth. It was also classed as Saheeh by Ibn al-Qayyim in I’laam al-Muwaqqi’een (4/317). I’laam al-Muwaqqi’een (4/317).