Psychology

No, it's not. The subject in which admission is sought must be an Honours subject. In B.Sc (Hons) a subject is studied in all the three years at graduate level.

Yes, you can pursue Ph.D from Germany as the degree certificate provided by IGNOU is valid world wide.

Forensic science is basically using the principles of science to solve and analyze criminal cases, whereas psychology is mostly the study of the human mind and tries to determine the psychological factors which lead to the crime. Both of them deal with the legal system but employ different methods in their application.

If you are interested in psychology then you can go for that too because mass communication and psychology provides good job opportunities.

Yes it does, for details please see:
https://www.shiksha.com/humanities-social-sciences/psychology/course/m-a-in-psychology-andhra-university-visakhapatnam-269572

Candidates should clear Bachelor's Degree in Psychology or equivalent, with a minimum 55% marks in aggregate or equivalent grade point average.
Students who have completed Bachelor's degree with Psychology as a core subject (completed minimum 60 hours or equivalent).

Following are the top colleges for Masters in psychology:
DU
Government College of Educational Psychology and Guidance, Jabalpur
Deen Dayal Upadhyay Gorakhpur University, Uttar Pradesh
University of Calcutta
University of Madras
BHU