Hello Abhey

To be more precise then Yes it is sufficient to get good Marks but to be in topper's list List then it is not.

Yes, you can rely on NCERT for Chemistry as it is more than enough for Both Manipal and BITs but for other Subjects like Physics and Maths you need some variations in the questions.

Manipal is ok but if you have prepared well bot JEE then there is nothing to worry about BITS.