Colleges in Kolkata

Yes, you will, but the pay would depend on many other factors

Write NEET, get a good score, and then apply for a medical seat.

Yes, B.Ed Course Eligibility:
A minimum aggregate score of 50% in graduation is a requisite for admission. A minimum aggregate score of 55% at post-graduate level is mandatory for admission into colleges for the B.Ed curriculum.

Yes, you are eligible, provided you have the necessary marks.

It's not strict that you have to choose a hostel. It's up to you. Colleges cannot force you to stay at their hostel, you can go to court against that.

It depends on your ambition, I mean where you want to see yourself after the completion of the course. If you are more towards banking, insurance accountancy or finance related in terms of interest, then Finance can be good choice. But if you are more interested in aspects related to market and market scenario as well as about market segments and you have ideas aggressive enough to please a customer, then Marketing is not a bad choice.

No, but to get admission you have to apply through tha scores of JEMAT CMAT.

Yes, you can. You are eligible for the same.

Aspiring students should have completed class 12th HSC/10+2 (or equivalent Level of Examination) from any recognized school board.

Yes, you can get admission in Diploma in Computer Science after 10th and many colleges provide this course. But the percentage criteria is not fixed, it is different in every college.
There is a university Dr. CVRU in Bilaspur(https://www.cvru.ac.in/) which provides a Diploma in CS and the University does not have any minimum percentage requirements. I have also completed my Diploma in CS with this university. And my experience with the college is so good, the faculty of the college is so good and also helps a lot. In the end, I get a decent placement. You should also visit the college before taking admission anywhere.
Best of luck.