CBSE 12th

Yes, you can get admission. You are eligible for that so move forward.

After 12th commerce, you can do one of the following:
B.Com
CA
BA
Law
BMS
Hotel Management
Bachelor of Statistics
Company Secretary
Hospitality Diploma
Animation and multimedia
Journalism
Mass communication
Fashion Designing
CMA
Bachelor of Economics
Event Management

Dear Utkarsh,
In order to get admission in DU through DU JAT exam, you must have maths as a compulsory subject in class 12th.
Hope this helps.
Good luck.

Please refer to the link to know the details about the hostel:
http://www.riemysore.ac.in/hostel-for-students/

Please refer to the link provided below for details regarding admission process followed to secure admission in Tolani Maritime Institute for B.Tech. in Marine Engineering. Eligibility criteria to qualify for admission for this course is also mentioned at this link. Regards.
https://www.shiksha.com/b-tech/course/b-tech-in-marine-engineering-tolani-maritime-institute-talegaon-dabhade-pune-71248

You can opt for MBBS, B.Pharm or B.Sc in agriculture as all three have good career prospects.

Yes, you can get B.Tech CSE in Amity, Noida as the eligibility is 60% marks (PCM and English) for general category candidates.
JEE mains: Students securing a score of 30 and above in JEE Mains 2017 plus 60% in E-PCM (English+ Physics+ Maths+ Chemistry/ Biology/Computer Science/ Biotechnology), will also be considered as eligible for direct admission process i.e., exempt from entrance test and interview for B.Tech programmes only.

It all depends on your AIR. Given that, you got 71% in JEE Mains, I am assuming you have a score of 255-256 which brings you a rank of around a maximum of 3K which means you have a guarantee to get in DA-IICT. The cut-off ranks are around 12K.
Hope this helps.