NIT

Hello Aneesh Babu, you indeed have obtained quite good percentile. Last year the cutoff for OBC-NCL was just above 72. If same continues this year, I am sure that you can get admission in one of the NIT's. Be that as it may, I would like to advise you to appear for further sessions of JEE Mains to improve your percentile. This time it should be fun since you can not loose anything!
Best wishes to you.

Yes, there is a very good chance of getting admission as you get a good percentile, and belonging to the OBC category. You may be selected.

Yes, sure you will get a seat in CSE in Chitkara University.

Hello Suraj Sutradhar, you need to appear for JEE Advanced before admission process starts for even NIT's. JoSAA is the agency that processes the whole process of admissions into IIT's, NIT's, GFTI's & IIIT's. You need not appear for JEE Advanced if you do not intend to bid for admission in any of the IIT, but definitely need to appear for it if you intend to do so. Best wishes to you.