CBSE 12th

Yes, absolutely if you are unperformed or failed in any of your exams, CBSE offers another chance to all students to better their results.

It depends on what you have taken in your PUC. If you have taken NEET then you can for doctor courses. If you have taken engineering you have plenty of options like ECE, EEE, civil, CSE, mechanical, etc.

You can go for DMLT, X-ray technician, D.Pharma or nursing after 12th with biology.

For vast knowledge Trueman is good. I am using Trueman and Pradeep both for teaching. I have found that Trueman is slightly better than Pradeep.

There are many institutes and organisations offering courses in robotics which can be pursued after you complete your 10+2 studies. Please refer to the link mentioned below for eligibility and scope of taking up a career in Robotics:
https://www.shiksha.com/b-tech/articles/your-career-after-robotics-blogId-4610

Even if you haven't opted for maths in higher secondary you can take BCA as your grad but, in most of the cases, maths is one of the two general papers for BCA in college. So, it would be better if you choose a college and find out their general subjects with BCA. Grad level maths is a bit tough but not for those who have studied it in HS.

I guess you would find maths in most courses, however you could try courses in Arts or humanities.
Arts, Humanities & Social Sciences Degree Guides
History Degrees. Psychology Degrees.
Philosophy Degrees. Sociology Degrees.
Social Work Degrees. Archaeology Degrees.
Sports Coaching Degrees. Political Science Degrees.

It would be little difficult because you need speed for the JEE examination and for that you need to learn short cuts and various tricks, even if you want to self-study, then enroll for mock test papers and online tutorials of some good coaching institute.

For details about the admission criteria please visit the SPJIMR website:
www.spjimr.org