CBSE 10th

VIT accepts VITEEE rank. No admissions are based on JEE score. You have to get a minimum of 60% in 12th to get admissions.

Use rank predictor to get a rough idea of your rank and percentile.
https://www.shiksha.com/b-tech/resources/jee-main-rank-predictor
Then, use the college predictor to know about the colleges:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

Eligibility Criteria for admission in Diploma in Audio and Music Production - Candidate must have passed 10+2 from a recognised board.

Don't take instant decision. You have sufficient time for thinking.
IIT Bombay
IIT Madras
IIT Kanpur
IIT Kharagpur
These are the top colleges of aeronautical engineering. So, well in your +2 exam and after that give IIT exam.

Eligibility Criteria for admission :
Candidate must have passed 10+2 from recognized board.

Foreign universities have their own admission process. Your scores are decent. Shortlist few colleges in Germany. Checkout their course and syllabus. Select few colleges where you would like to apply. Prepare for the entrance exams which they consider. Do well in exam. Proceed with admission process. Every college will have a different criteria for admission. You need to check it on their website. All the best.

D.Ed: Eligibility
Listed below are the minimum criteria which candidates interested in pursuing the course are required to fulfil, in order to be eligible to apply for the course. Successful qualification of class XII from a recognized educational Board. Preferably, Humanities subjects as the main subjects of study at the 10+2 level, and a minimum aggregate score of 50% (45% for SC/ST/OBC candidates). The minimum age limit is 18 years and upper age limit is 36 years. It is relaxed by three years for OBC and five years for SC/ST candidates.

Yes, you are eligible. Also, you need to have 90%tile in CAT.

It is good that you have set a goal and have started to think of how to achieve it from now. If you are going to do class 11 and 12 from CBSE then I think you should take up humanities (if you are very much sure that you will not change your mind later on) as you will have an opportunity developed as base in social science. Then you can do BA and take coaching for UPSC simultaneously so that you might not have to take a drop.
Also, try to make notes of editorial column of the newspaper daily and try to think of the topic in different view i.e. how can it effect socially, economically, etc.

Yes, but you must have done B.Sc in either chemistry or biology.