Germany

Few of the top universities in Germany - Technical University Munich, University of Freiburg,Hochschule Furtwangen University, Humbolt University of Berlin, Freie University of Berlin, RWTH Aachen University and University of Göttingen.
Regards

Hi Gaurav,
Possibilities are less. A CGPA of 8 and higher is preferred. You may take the GATE exams and apply or apply to countries less competitive than Germany.

there are many search on net

Yes, and besides you also need to learn German language.

Dear Mohit, you can consider Queen Mary, Cranfield and
Glasgow Caledonian University in UK. In Germany RWTH Aachen University is the best option you can consider. There is another degree offered jointly De Montfort University,Leicester in collaboration with the Faculty of Mathematics
and Engineering at the Fachhochschule Bielefeld (University of Applied Sciences) in Germany. Check all the website for complete information. This programme is an advanced modular programmefor graduates of mechanical and electrical engineering, includes a research project and financial aid too.
Best Wishes

Lateral entry in engineering will not create any problems for admission in German Universities for MS provided your degree is from a recognized university in India.

Dear Nilesh, Germany is a better option for all good reasons. I am not aware of Estonia universities as Germany is more popular. Work permit and PR options are open to international students. If you want to settle down, irrespective of the county you must be qualified and skilled.
Best wishes

No, they are not compulsory but having either one of the scores is an advantage no doubt.