CBSE 12th

Hi,
Its a wrong information. 12th marks+ NATA scores are considered for merit seats. For Management quota seats, minimum of 55% marks in 12th + NATA is required.

Go for NDA coaching and clear NDA exams.
Every year, NDA exam takes place twice and is named NDA I and NDA II. This exam is having two papers of 3 hours each.
The first is of mathematics and second is of English with GK.
If you crack that exam, you will get a call letter from SSB.

IIM Ahmedabad? IIM Ahmedabad does not offer Architecture.

Your HSC board exam doesn't matter for engineering college, you have to qualify for the entrance exam of engineering college.

It will depend on the field which you want to choose or which field/subject you are interested in.

Dear,
There are a lot of options in which you can make your career but choose the field according to your caliber and interest.
Fields are:
English (Hons)
BALLB
International relations
Psychology
Philosophy
Sociology
Foreign language
Journalism
Fashion design
BFA animation or visual communication
All the best

To become a space scientist, you need to get admission into an institute offering B.Tech in aviation/aeronautics. You need to clear IIT-JEE Mains and Advanced to get into IITs or IIST-Trivandrum.

You do stand a chance of getting a call. Work experience, extracurriculars add a cherry on the cake.