Certificate

Hi Sri,
If your rank is under 50,000 in JEE Mains, then you can easily get admission in nits. As per your score in JEE Mains, you can expect a seat in NIT Patna, NIT Puducherry, NIT Srinagar etc. You should predict other possible colleges here:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
Best of luck.

Some of the best institutes in Delhi are-
Aptron
Network Bulls
Netexperts
UniNets etc.
Good Luck.

Hi Akhil,
No, you will get all the certificates together. Instead of eight semesters, you will have to study for ten semesters. Every semester has its own results. In last average of ten semesters will be your degree marks in total or aggregate.
Best of luck.

Hi Aman,
You can get good private colleges with this score like LNCT Bhopal. You should predict other possible colleges here:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
Yes, if you have other states certificates, then you will be treated as general.

There is very less chance to get admission in NIT Trichy even with sports quota. NIT Trichy is top 2 and NIT in India, so it is difficult.

Hi Monty,
You are fail in a particular subject, so you should apply for the supplementary or compartment exam for the same. Because without clearing all the subjects, you result will not be considered as pass. Please solve some sample paper and give the compartment exam. After that only, you can get admission in higher classes.
Best of luck.

Fee will be 90 thousand per annum.

No, DTU won't accept SC certificate issued by West Bengal government. Get a SC certificate under central government rules and regulations. A state undersigned caste certificate is valid in the particular state only. You need to get the caste certificate under the law of the government of India for admission in Central Universities and other states.

You can write a application for school authority to give duplicates certificate.
Good luck.