Civil Engineering

Evening/distance/online/part time engineering courses are not valid any more as per the latest supreme court verdict, hence would recommend you to join regular B.Tech course for better career prospects.
http://www.tribuneindia.com/news/nation/no-technical-education-through-correspondence-says-supreme-court/491819.html.

Go through the KCET college predictor below for details to check the probable list of colleges:
https://www.shiksha.com/b-tech/resources/kcet-college-predictor.

Check out the college/stream reviews below for details :
https://www.shiksha.com/college/techno-india-college-of-technology-rajarhat-Kolkata-48632/reviews?course=250517&sort_by=year of graduation&type=question
(Copy paste the entire link on the browser).

https://www.shiksha.com/b-tech/resources/mhcet-college-predictor
Click on the link. This will surely help you.
Best of luck.

The basic eligibility for this course is a pass in 10+2 with subjects like mathematics, physics, chemistry, biology, etc.

You have thought correctly. Pursuing MBA depends a lot on your interest areas & career plane. If you want to move into general management then MBA is good. However, if you want to continue in your technical field then you could pursue M.Tech. Later once you have experience in your technical areas you can pursue MBA to get an understanding of management principles & leadership.

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.

You need to apply for Lateral Entry programme in a university like in Lovely Professional University has it, or DIT University.