Yes, it is possible to score above 70% at North Bengal University. I have known people from the university who have scored above 70% and even 80% in their subjects. But it also depends on your subject. If it’s a science subject like Physics, Mathematics, or Computer Science that's achievable. But it’s a little tough for Arts subjects.  Also, recently NBU started a semester pattern and study. In the semester system, the question pattern was updated and it makes scoring above 80% easy.  

Calcutta University is far better than North Bengal University for studying law.  CU has more national recognition as compared to North Bengal University. The exposure you will get at CU is unparalleled. CU is an older university compared to North Bengal University. Although you can excel in your academics from any university, choosing a better one will provide you with more exposure. So, if you are interested in pursuing a degree in Law, I will suggest that you choose CU. 

Here is how you can collect your transcripts from North Bengal University. Go to the university. Take all your documents like mark sheets, degree certificates, and colored photocopies with you. Get an application form from the university. You will have to pay challan for each document. It is around INR 1000 for each. Make a DD in the name of the university and submit it at the counter.   Pin all your documents with the application form and submit them at the counter.  Your transcripts may take 30 days to get ready. You will have to do follow-up calls to know whether it’s ready or not. You can visit the university to collect your transcripts or get them by courier. 

Calcutta University is the best option for doing an M.Sc in Physics and here is that preference order that you should follow. Calcutta University Burdwan University Visva-Bharati University North-Bengal University Also, you should know that irrespective of which university you are taking, you will have to study on your own. You may get assistance from your professor or your friends. However, you will have to put in the extra effort to do well in your academics and get a job.