CBSE 12th

Yes, you can take classes for banking but it will be better if you take your 12th seriously because you have such subjects which need more attention.

yes it is true. official notice from MHRD= http://mhrd.gov.in/sites/upload_files/mhrd/files/ChangesJEE2017.pdf
75% for general and obc-ncl.
65% for Sc and St

You can do B.Tech or B.Sc. in physics honors for the same.

You are eligible for some colleges.

Hi,
Firstly, you have to appear for JEE Mains exam which is of 360 marks with 90 questions. If you clear that exam then you will be successfully eligible for JEE Advanced. JEE Advanced is one of the toughest exams.
All the best.

No, you cannot appear. As per the rules, student appearing in improvement should not be engaged in any higher education. For more details you can visit improvementexam.com.

You are in 12th. So now you must follow a systematic plan for your studies. It is better to classify as to which subject you find typical. After that you must allocate suitable hours of study to that subject. It is also advisable to prepare for your 12th after viewing the blue print of the exam. Try to completely prepare first those topics which you find easy and also those which carry more marks into the blueprint. It will boost up your confidence. I hope this helps. Kindly feel free to revert with any further queries.

Yes, you are eligible for B.Com after PCB in 12th.

Students who did not have computer Science in +2 stage are eligible for B.Tech CS and will not face any problem during studies of CSE. Currently it is a good career option.