Engineering

Yes, you have good chances of getting top NITs and other top engineering colleges. Check the below college predictor link for the NITs which you can expect:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=8030745

Trichy, Surathkal, Warangal, and Allahabad are the best NITs for Chemical Engineering.

It completely depends on your area of interests, competitive exam in which you appear and the main criteria is your Rank and Marks. If you have scored good in exams you will definetly deserve a seat in reputed college which has good infrastructure and faculties along with decent placements.So all t

Check the below link of the college predictor, check for colleges based on the JEE Mains rank and category.
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=8030745
Also, do check for state engineering colleges accepting JEE Main

It will be difficult to get NIT with this score. Also, look for state engineering colleges accepting JEE Mains score. You can check the below college predictor:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=8030745

You can look for state engineering colleges for mechanical engineering discipline. You can also check for government colleges OBC-NCL quota. This might help you.
Check the below link for top mechanical engineering colleges:
https://www.shiksha.com/b-tech/ranking/top-mechanical-engineering-colleges-in-

There is no need for paper 2. You can apply.

As per me, INR 1.25 lacs per semester. The fee increases by 10% each year that is after every 2 semesters. There may be some concession in the fee if you scored 85+% in class 12th.
Good luck.