Technical University of Munich

I think it is easier in comparison to other universities because they don't really have a limited capacity and can admit students purely based on merit. There should be some requirements posted on the website, and if you fulfill the requirements then you'll be admitted. For more details, you can get in touch with the placements companies as they would have all details about the same.

Diplomas are not accepted. Clear IIT JEE Advanced or enroll into Studienkolleg.

To study civil engineering, the best institute is TU Munich.

It all depends on your test scores and the scores that you've got in your last college/university attended. All this will decide if you will be selected or not. Check on the website and apply.

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.