NIT Eligibility

I don't know about the reservations, but for admission in a good NIT, you don't have to wait for the JEE Advanced score, you can get admission to the college by getting at least 250 marks in the JEE Mains exam.

Rank near to 1500 in general-PWD category can get you a seat in NITs for OBC and SC/ST PWD category marks required are even slightly lesser.
All the best.

For IIT, it is 75% and is the easiest part of it. If you want to join IIT, you need to crack JEE Mains and JEE Advanced as a good rank in advanced can get you a seat in IIT. Though you must be eligible for NIT if you get your expected marks, but to get a seat there, you need to perform well in JEE Mains.
All the best.

You are eligible for NITs like MNIT Jaipur, NIT Silchar, and NIT Kurukshetra but not for NIT Warangal because for pursuing MBA from NIT Warangal one must have an engineering background.

Also, it depends upon on your JEE Mains marks and cut-off of the respective college.

There aredifferent cut-offs for different categories but if your score is above 150, you will definitely get a good college.

You have to score at least 75% marks to get admission in NITs, IIITs etc. But, you can get any other government or private engineering college based on your rank.

Yes, of course you are eligible. I would like to tell you, from this year on wards, the weightage of class 12th marks has been removed, so you need not to worry about your marks. Just prepare hard and enjoy.