CBSE 12th

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.

IGIA offers CPL training with its associates in India, USA, Canada, Spain, New Zealand and Australia. You need to be 12th pass in Math and Physics. The CPL can be done for an investment of around 23 lacs for a single engine training and around Rs 28 lacs for a multi-engine training. CPL is not a semester wise course and the fee can be paid in the installments. Almost, all the leading banks offer loans for pilot training. You can visit:
www.igiaindia.in

He can pursue B.Sc in Home Science or BHM.

It depends on the school. Till the time the school has not given the forms to CBSE, you can change the subject.
Ask your teachers.

Email about the same to the college.

You need to discontinue B.Sc if you want to pursue B.Tech in IT. You will have to take admission in the 1st year of B.Sc in IT.

Your UG percentage is good, you should try for CAT to get a good college for MBA.

You can get the job of a JE with Diploma course, so take entrance exams for JE.