CBSE 12th

Yes, you can get admission in NITs.

You should secure more than 55% to be eligible for IPM.

If you want to make your career in arts or literature background then you can choose BA programme.

Students with commerce background and with 40% in 12th are eligible to apply for this course.

You can pursue B.Sc in maths only when you have science stream in 12th mainly mathematics and minimum of 50-60 % to be eligible for admission in programme. So now you will not be able to pursue as you have commerce in your 12th. Please choose different options for your career perspective.

No, you can't do it because you don't have science stream so I would like to suggest you go for CLAT. It will be different from the subjects or streams which you don't like.

You have to be sure in life as what you want to do. Explore new areas of commerce stream along with many options such as BBA, B.Com, CA and CS. You have another option to pursue a career in statistics as you have studied mathematics.

You can take IPMAT exam after class 12th for IIM-Indore or complete the graduation from any university and start preparing for CAT exam from day one of graduation with full concentration.
Hope it will help you.

Yes, you have two options on the basis of two different subjects that is physics and biology. Firstly. if you really like biology then you may proceed with the medical entrance exam and furthermore, you can do B.Sc in physics to become a well-known physics professor. In spite of all these, you have a good chance of doing physiotherapy as you like both biology and physics. And physiotherapy also needs these two subjects strong. My opinion for you is physiotherapy as this is one of the most developing courses today in the entire world.