Technical University of Munich

Your class 12th percentage must be above 75%. In Germany, universities ask for 13 years of education but in India, we have 12 years of studying experience. So you have three options:
1. Clear IIT-JEE Main and Advanced
2. Spend a year at a university in India
3. Do Studienkolleg
After that, you need to pass TestDaf up to level c2 to prove your knowledge of the German language. The chances depend on your marks. You can apply via university assist.

Both are good but TUM is ranked above TUB.

Yes, you can, but please check requirements on the website.

You must attain C2 level in the German language.

Please check the university website. You must also know the German language.

For TUM, GATE score should be high enough. But writing only GATE is not enough, you have to write GRE tougher and trickier than GATE to study abroad.

As the college has not disclosed the number of seats so I would request you to drop a mail to the college officials.

Hello Kumar,
GATE scores are accepted however not mandatory and for MS programs not Bachelor's degree. To study Bachelor's you must clear IIT-JEE adv because German universities require 13 year education not 12.

You first check out the detail of admission in the institute website:
http://www.tum.de/en/homepage/.
Or, you can search the process in Shiksha Study Abroad.