B.Sc

The degree is usually mailed after 4 or 5 months of publishing results. This could also be delayed by various reasons. You should better contact the university and tell them that you haven't recieved the degree yet. They will tell you all necessary information.

Bankura University, Bhairab Ganguly College, Dinabandhu Andrews College, Garhbeta College, etc. are few colleges in West Bengal.

Some of the best courses are PPE, NIIT Accenture, Tracxn, Electronics and Embedded Developer, etc. It depends on your interest which course you do. Basically, all courses are important.

The fee structure of B.Sc Electronics is Rs. 39,000 and including the hostel charges, it will be a thousand rupees more.

You can pursue your B.Sc in FN at Madurai Kamaraj. It is a recognised institute. https://www.shiksha.com/science/course/b-sc-nutrition-and-dietetics-directorate-of-distance-education-madurai-kamaraj-university-287463.
https://mkudde.org/ug_courses.php

Since the admissions are over this year, you can only apply next year now. You will need to apply online on the official website of Christ at https://appstat.christuniversity.in
Then, you will give exam and based on your result, you will be allotted a college.

You can pursue 2 regular courses together. That will be illegal and may cause you some serious problems in future. What you can do is that pursue a course through correspondence or distance from recognized institutes like IGNOU etc. And pursue another one through regular mode.

The classes have started by now and there is no information online about the seat vacancies. You will have to contact college now to know if it is possible now.