JEE Advanced

You do not have any chance without JEE.

Among your choices, DTU IT is a very good option unless you want IIT brand attached in your CV.

yes it is needed for joining IIT not other institute. you will appear mains but you will not able to appear advance if you did not have minimum 75% inboard.

if you are general then no or if you are sc/st then yes!

JSS doesn't have any management quota.

I think under 1200

Your CRL rank must be 2000-5000 to grab a good IIT with mechanical branch.

It depends on category and you should be in top 20 percentile of your category in board exam. It differs every year .

Avinash,
Check the link below to know the colleges that you can get with this rank:
https://www.shiksha.com/jee-mains-college-predictor
Also, using your rank, you can take direct admission in some good private university. These days we have so many good private universities also imparting quality education to the students around the world. They offer you admission on JEE scores/ tests conducted by them/ your marks in 12th. Some of these also offer good scholarships based on any one of the above mentioned admission criteria.
Check the websites of some good universities or call on their toll free number for more details.
Good luck.