University of Madras

There is no percentage mentioned by the college. You need to have passed graduation from recognized university.

Yes, you are eligible to do M.Sc in maths.

Madras University offers BA in Criminology and Police Administration through distance.

Yes, visit the below link for all the details related to the course:
https://www.shiksha.com/humanities-social-sciences/course/b-a-in-criminology-and-police-administration-institute-of-distance-education-university-of-madras-chepauk-chennai-289332

Eligibility for B.A. in criminology and police administration in UNOM is:
The candidate must have passed his/her 10+2 from a recognised board. Admission is based on the marks obtained in 10+2.
For more details: https://www.shiksha.com/humanities-social-sciences/course/b-a-in-criminology-and-police-administration-institute-of-distance-education-university-of-madras-chepauk-chennai-289332

You can refer:
https://www.shiksha.com/arts-fine-visual-performing/music/course/bachelor-of-music-institute-of-distance-education-university-of-madras-chepauk-chennai-289350

As per NCTE norms, regular teachers working in primary, middle, secondary or higher secondary schools in Tamil Nadu, recognised by State / Central government, with a minimum of two-years teaching experience are only eligible for admission into Annamalai University distance education B.Ed course.