Test preparation

Admission to IIMs is via a common entrance examination called CAT. After clearing the entrance examination, based on your score, past academics and relevant work experience IIMs shortlist students for written ability test & PI where they will gauge your interest for pursuing MBA. After clearing the same, one gets admission to any of the IIMs.
Good luck!

First and most important tip for any exam in India, practice previous year question paper. I am providing you link to buy the book:
https://www.amazon.in/Guide-NIFT-NID-IIFT-2019/dp/9313164418/ref=dp_ob_title_bk
Questions in NIFT are often repeated especially in GAT and CAT part.

For Organic chemistry, Arihanth is best problem solving book.

As per my opinion and my knowledge, you cannot go for Science. As per my opinion and my knowledge, you must go through internet, as there you can find previous year question papers and all that will help you much better than any other books. So, go for it. All the best and have a great life ahead.

Coding is the heart of the CSE. You can't develop any thing without it in CSE. For less coding,
Cyber Security
Computer Graphics
Web Technology (Development)
are required less coding or easy coding technique.

Dedicated preparation with honestly followed time tables is most important thing. Issue is, you need to reduce your negatives and increase the number of correct answers that you achieve by practice of questions and revision of course again and again.

Getting a BDS seat is going to boost your confidence level. Giving another try for NEET, AIIMS and JIPMER can get you a 600+ score.
Chemistry will be responsible for your selection and physics will give you high ranks. Keep on revising each subject, make timetables and complete each and every important topic from biology like plant, human physiology, morphology, diversity, ecology and reproduction in animal and plants.

Yes, MBA can help you sharpen your skills in business management and thus assist you in the professional career. However, keeping you interest areas in mind, you need to decide what you need to do from a career perspective. The chances of doing well in a career of one's interest areas are much higher.

Hi Radhika kundapur, Please click the link below for preparation and syllabus of KTET. https://www.shiksha.com/teaching-education/exams/kset/syllabus.