Uttarakhand

Surely Delhi because of its better quality of studies and better colleges than Dehradun such as IIT, NIT, DU, etc.
Good luck.

It is good. You can go to this website fore more information:
https://tulasinstitute.edu.in/courses/btech/

UPES, Dehradun is the best college for CS.

Both the institutes are equally good, but to know the exact scenario for faculty and placements, you should get in touch with the current students through social media or in person.

You will repeat your 12th provided the school gives that option. Changing the subject in grade 12 is very difficult so you need to write to the state board for the options available to you. If that's not possible, you can register with NIOS to give exams for biology only or other subjects also to improve your percentage.

This is very good program for IAS aspirants. Students having a minimum 50% marks in 10th & 12th can apply for this course. And, admission is through Counselling and Interview. More details you can see on its website. All the best!

If you are not confident of cracking JEE after one year drop then DIT B.Tech IT is good option. If you work hard and be in first 10% of your class then it will help you to build good career.

IES, Bhopal is a better college.