Exam

You can go to college predictor for the same
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
good luck.

No, there is no entrance exam for B.Sc physics. You can get a seat. Merit list would be prepared on the basis of your class 12th marks.

You can get admission to B.Tech on basis of your JEE rank. There is another government college IGDTUW Indira Gandhi Technical University for women, Kashmir Gate. One of my friend got 6000 rank in her JEE. She took admission in IGDUW B.Tech software engineering. There will be councilling session. You can try. In Delhi there is IIT also for admission to engineering where your JEE advance rank would be considered. You can look for private colleges also like Amity and Sharda university. All the best.

You should consider following link:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
Use this predictor and find weather you can get admission with your rank.

Yes, you can take UPSC exam. You are eligible for the same. Good luck.

Yes, you can get admission here for this course. You are eligible for this. Good luck.

https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
Use this link for college predictor.

You have to appear in one exam only. Good luck.

Yes, he can get admission here.
Good luck.