IIT

Yes, those are included in the syllabus and will be covered mostly in the first 3 semesters.

IITs don't offer B.Sc programmes, they provide B.Tech and M.Tech only.

No, there won't be any problem. They two are different from each other, IIT is an autonomous university recognized by central government while VIT is a deemed university.

If you are from general category then you must have 75% in 12th to appear for JEE Advanced.

To get admission in IITs, you need to have at least 75% in class 12th. For general category, it is 75% and for reserved categories, it is 65%. The lower grades will not make you eligible to sit for IIT-JEE Advanced.

There is no provision of top 20 percentile students to join IITs without appearing for JEE Mains.

Yes, it is possible. You have to believe in yourself, first then only you will study harder because getting through JEE Mains is quite difficult but not impossible. Study hard, clear all your concepts and make sure you crack both JEE Mains and Advanced exam.

Computer science is the best option followed by Mechanical and Electrical and Electronics.

Dear Anita Balakrishna,
Almost all IITs offer MBA programme, they do accept CAT score. Apply for all IITs, but they are specialised in operations and production area and not in finance and marketing. This is for your information. IIT Mumbai, IIT Madras and IIT Delhi are some of the best ones amongst. them.
All the best.

Which course do you want to pursue, Bachelor's or Master's?