JEE Main

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

If you want to get a good college and you have enough dedication and confidence. You should drop one more year rather than doing B.Tech and preparation simultaneously. B.Tech has its own wide syllabus, it will not going to be easy to accomplish both task together. If your college is good, then focus on your academic and learn skills to get future ready. If it is not you can dream and dare to get an IIT for higher studies. It will be a wise decision.

Yes, you can but your board exam's score will affect a lot.

Candidates shall be eligible for admission to the First Year of the Bachelor's Degree programme in Architecture or Planning if they have obtained at least 50% marks in aggregate with mathematics as a subject in the class 12th or qualifying examination. You should also have a good score in JEE Mains paper-2. So, you are eligible for admission.

Please refer to this link to get more insights of the colleges and branches. JEE Mains colleges:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
JEE Advanced colleges:
https://www.shiksha.com/b-tech/colleges/b-tech-colleges-accepting-jee-advanced-india. However, as per your rank, you will get very good colleges.

Sastra, Yes you can get admission in it easily!

You have good marks and percentile and will get any college. CSE is all about computer and maths if you don't like maths, then don't opt CSE.

It's quite difficult for you to get seat in NIT. If you belong to other category other than General, you might get a seat.

There is somewhat chances for your admission in NIT, Trichy but still you have to be patient for the rankings to be declared then only it will be confirmed if you'll get admission or not. Good luck with your future.