M.Tech

Based on your profile, MBA Logistics/SCM or PG Diploma SCM with one standard ERP certification will be best for your long-term career.

Hello Payal,
The following are the entrance exams for those who go abroad. The exams are:
1.TOEFL
2.GRE
3.GMAT ( for management )
4.IELTS
After qualifying them with the with eligibility criteria, you have to show the required bank balance then only you are eligible.
Along with bank balance, you must have a passport.
Instead of abroad, in India, there are also a lot of good M.Tech universities available. For doing M.Tech from IITs, you can write GATE exam.

It depends upon what hits you the most from the following points:
1. Interested in projects related to your field or want to do research on any part of your field? - Go for MS
2. You have a great knowledge about your field and you are in no mood to get deep into your studies , just want to earn well? - Go for M.tech
3. You are a leader and you feel like to have your own business some day or be a CEO to one of topmost firm ? - Go for MBA but not from any university located in germany.
Hope this helps. All the best.

Your question is very generic. Without being specific, you are eligible to seek admission in MS degree on completion of your Engineering graduation degree.

Yes, you can opt for avionics as the specialisation.

Acharya Institute of Technology - AIT
Akshaya Institute of Technology - AIT
Bangalore Institute of Technology
BMS College of Engineering - BMSCE
Christ University

Power electronics and drives.
Power system engineering.

No, GMAT is required for business related courses and GRE for engineering related courses.

Engineering physics (B.Tech) at IIT-Madras.

12 backlogs indicate your academic performance is below average, therefore, chances to get admission in MS in German universities is very poor. With 12 backlogs, it will be difficult to get good recommendation letter from your professors. You may revisit your career strategy.