CBSE 12th

Yes, if you qualify JEE Advanced with good rank.

I think, NATA score is needed for the same.

Yes, there is a good chance.

Hi Abhishek, I've heard lately about the good coaching classes provided by https://niveditaclasses.com/cbse-board-coaching/
You can visit the site and directly contact them.

Yes, you can apply for B.Sc in agriculture because it requires only 12th and does not depend on the stream in class 12th.
All the best.

Yes, you can go for B.Com (Hons) in some top universities like DU, JNU, BHU, etc.

Sorry, no chance in IIIT Delhi with this rank. Your CBSE score is good but, your JEE rank is not good for admission if you want CSE.

No, as the per the eligibility criteria mentioned by the college.
Please visit the link for better understanding: https://www.shiksha.com/it-software/course/bachelor-of-computer-applications-banasthali-vidyapith-jaipur-8978.

Applicants who have passed B.Com one-year with minimum of 50% marks are eligible to get admission in B.Com (Hons), while for admission to B.Com (general) course, the minimum eligibility criteria is candidates must pass 10+2 with any 4 of these subjects Mathematics/ Statistics/ Commerce/ Accountancy/ Economics/ Computers or any vocational subject under commerce stream.
Good luck.