Exam

https://www.shiksha.com/mba/mah-cet-exam
Refer the link.

Your score seems decent. I think you should be able to do that.

Raw scores in JEE Mains have lost relevance since last year and what matters is percentile. I am sure you know the percentile. (100- your percentile) percent of almost 9L students are ahead of you. From this you can find as to what could be your rank. But officially, NTA will be announcing rank only after April exam.

Your scores seems pretty decent I think you should be able to. Good luck.

I think according to your category you should be able to attempt Mains.

Engineering is a costly course in the country. I doubt if there are scholarships available for the course because even the IITs don't provide for the same.

A GRE score above 315 should be targeted and a TOEFL of 90 to 100. It is better you check some university websites for the admission requirements, you will be able to prepare in a better way if you have a target and goal in mind. Different universities have different criteria.

No, admission to B.Sc. is based on only merit basis, +2 marks in PCM.

I think you should be able to make it to the Mains. Your percentile seems decent.

Scholarships are based on merit, they are given by the universities (you are applying to) to deserving students. Generally applicants are considered by default and the most meritorious ones are considered. Very good academic grades, a good GRE score, above 310, TOEFL score above 100, extracurricular activities, SOP, recommendation letters etc. Are evaluated.