Masters

Master of Science Environmental Management colleges are:
Dr. BR Ambedkar Open University
IGNOU
Annamalai University Distance Education
JNTU Hyderabad
Bharati Vidyapeeth
Nalanda Open University

Yes, since you want to do a Masters in mechanical engineering, you may opt to give GRE exam and score around 320-330 and with a good resume you can opt for Masters abroad.

To do Masters in USA, you need to appear for the GRE exam and then score about 320-330 marks out of 340 and have a decent CGPA during college course.

Hello,
After completing BA, you can apply for following master courses:-
1) MBA in HR / Marketing / Finance / Financial Management etc.
2) MSW Master in Social Work)
3) MA
4) PG Diploma in Yoga
5) PG Diploma in Nutrition and Dietetics
6) PG Diploma in Cosmetology
7) You can apply for various languages certificate courses like German language, French language etc

Yes, you can do postgraduate Diploma in either of the subjects mentioned in distance or correspondence and for that use Shiksha's official college predictor to get a list of such colleges.

Yes, it is a good choice. You may want to try out Shiksha's official college predictor to get a list of colleges that offer distance education or correspondence.