JEE Main Percentile

Hello Megha,
In order to get admission in top ten NITs your rank in JEE Mains under OBC-NCL category should be under 3000 and to achieve this, your percentile should be above 98.6 and then you will be eligible to get seat in top NITs.

You have to take JEE Mains exam, according to the ranking only seats announce.

Yes, you will get INR. 50,000 scholarship every year.

Sorry. According to me you don't get any nits or iits.
It will be tough to get good government colleges but you can try for some good private colleges. I am attaching a link which will predict the best college according to your rank.
Try the college predictor:
https://www.shiksha.com/jee-mains-college-predictor

You can check the probability of getting a college here:
https://www.shiksha.com/b-tech/resources/jee-main-rank-predictor

You will get a lot of college in which you will get admission on the basis of this rank. So, I will suggest you to go for COMEDK once and check if are you getting top college or not, then decide for other college.

Yes, you have chances to get admission in NIT Surat.

Yes, there is strong possibility of getting a good NIT for your category score. You should be calm and choose the list if colleges wisely and go till last round of counseling it will be helpful. You can check out this link for prediction of colleges. https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor.

I think, you'll be able to make it to the lower NITs, because the cut-offs these are very high.

You have scored very well. Just hope for the best and proceed. If not wait for few counselings and achieve the best.