CBSE 12th

Yes, you can go for improvement exams because the minimum eligibility criteria is for getting admission in IITs, NITs and GFTIs is 75% in 12th class. Or, you should be in top 20 percentile of respective board.

Hi Manaswini!
You can explore the best possible career options for you by visiting this counselling webpage https://www.shiksha.com/careers.

You need to give a common entrance test or either you can get into this college by management quota.

What about CAT score? If the score is above 90, then there would be high chances and this would be for the interview call not the final selection.

Unfortunately, Cochin University do not offer any undergraduate programme in marine biology. Please check the link for more info:
http://cusat.ac.in/dept.php?deptcode=marinebio

Yes, definitely, you will get admission in MITS. Even you are good in your academics too. So, there are huge chances of getting this college. Even its one of the best engineering college in Andhra Pradesh. So, try hard and achieve the best.

Yes, of course. You can get admission for any graduation.

It is best, if you pursue MBBS from abroad (European universities are also good), but make sure those are MCI recognized. In India, it is difficult to pursue MBBS from private universities, because of high tuition fee charged by the colleges. Dropping a year and preparing for NEET will not be a good idea. But, if you are 100% sure about yourself, then you will definitely get admission next year. Go ahead with NEET. All the best.

Yes, best 4 percentage matters.
You just need to have a passing mark in the 5th subject.