IIT

To get admission in NITs and IITs, you need a strategy. You need to make your basics clear and rigid so that you can move forward. You can read NCERT books. You should practice as it will help you to understand the theories in a better way and also you will come across some unknown methods to solve a particular problem.
You can collect the previous year question papers with their solutions as it will help you to analyse the pattern. You should revise the areas in which you are strong, but work on the areas in which you are weak.
Best of luck.

BITS-Pilani, VIT University, Manipal University, Thapar University, SRM, BIT are recommended options. You may refer to following link for ranking of top engineering colleges in India: https://www.shiksha.com/top-engineering-colleges-in-india-rankingpage-44-2-0-0-0

There are some coaching that offer free IIT preparation by conducting some exam for their coaching institutes. By giving those exams, you can get admission in those institute that will lead you to free coaching.
Examples are: Super 30, Anand Kumar Institute, etc.

It is a newly started program in IIT and it will take some time to get momentum. However, considering reputation of IIT, you may expect average package of Rs.5 LPA.

You need to qualify JEE Mains exam to get admission in NITs and JEE Advanced exam to get admission in IITs.
Kindly visit the link mentioned below to know about the colleges offering B.Tech in biotechnology:
https://www.shiksha.com/top-bio-technology-colleges-in-india-rankingpage-54-2-0-0-0

My recommendation on your choices is as follows in order of precedence: IIT, NIT, VIT. These are based on brand image, career opportunities, growth and other factors.

Hi,
It entirely depends on the cut off of that particular year. But getting 230+ would ensure your admission in CS in good NITs. In case of IITs you need to just qualify JEE Mains but have to do well in JEE Advanced.

Different IITs are good for different branches. You may use the following link by changing filter to get the best IIT with respect to major branches of engineering: https://www.shiksha.com/top-engineering-colleges-in-india-rankingpage-44-2-0-0-0

You have to appear for JEE Advanced to get admission into IIT. In JEE Mains you have to secure a very good score, so that you get eligible to appear in Advanced.