JEE

See, books doesn't matter, what matters is how much concepts are clear to you. Also, how would you be able to think analytically.

Yes, you can get admission in that college but you can face some problem if you don't have home state quota.

Yes, he can get NITs but not any of the IITs.

BITSAT, UPSEE, VITEE, WBJEE Code-K and MHCET are the major ones.

It's your choice if you balance between your school study and JEE preparation then you can start preparing for it in class 10th.

There are centres of renowned coaching institutes like Aakash in Haryana itself in Gurgaon and Narnaul. There will be a centre soon opening in Rewari too. I guess there is one in Rohtak too. Class 9th is too early to prepare. For now, just focus on your school and make your concepts and basics strong. You can go for coaching in class 11th and 12th.

Here is the link:
https://www.google.co.in/url?sa=t&source=web&rct=j&url=https://www.shiksha.com/b-tech/resources/mhcet-cut-off-predictor&ved=2ahUKEwiI59nJvobaAhVLpI8KHUeWBnQQFjAVegQIBxAB&usg=AOvVaw3_igmRyVhCLPYQ1-xCi9Q
But one more thing about the cut-off, it can fluctuate by a few marks more or less.

Also,if you got under 100 rank you can and get 100% scholarship in tuition fees.

For admission in any college, JEE Mains marks are considered of that year in which you are applying for admission. There is no importance of previous year's marks of JEE Mains and Advanced in the admission process. Thank you.