CBSE 12th

To get admission in B.Tech you have to qualify JEE Mains or any other entrance exam to get into an expected college. You may get admission in B.Sc courses or any Diploma course.

Yes dear, you can very well give this exam next year but first focus on your class 12th marks.

By taking biology as an optional subject.

To get the information about the commercial pilot training course, kindly visit the link mentioned below:
https://www.shiksha.com/career-in-commercial-flying-all-you-need-to-know-article-13472-1.

Yes, the college accepts students from NIOS board too as it is a recognized board.

Hello,
In my point of view, you should go with BA in economics because economic has many options. There are many course after graduation in economic. actuarial science, Indian economics services, law, economics and its related disciplines.
Financial economics
Labour Economics
Agricultural Economics
Business Economics
Banking Economics
Development Economics
Therefore, we can say that B.A. Economics is a vast course that provides extensive knowledge about the practical and technical concepts that run the world.

Yes, you can get admission in SASTRA for B.E in Computer Engineering college at this score and rank but for that you have to wait till the last round of the counselling.

Hi,
Please visit Shiksha.com's college predictor-
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor. Ranks keeps on changing every year and differs from one branch to another and one college to another. If you fulfill the eligibility criteria of the specific institute, you may complete further admission formalities. For now, I would suggest you to first contact the institute officials of the shortlisted universities directly for specific eligibility criteria details.