IIT

There are some good private universities like SRM University, VIT University, Manipal University and many good colleges in NCR and other parts of country for engineering courses.

The Indian Institutes of Technology (IITs) are autonomous public institutes of higher education in India. The IITs have a common admission process for undergraduate admissions, called IIT-JEE. Minimum qualification for appearing in examination is 12th pass with science steam. The post-graduate level program that awards M.Tech and MS degrees in engineering.

You need to give the JEE-Mains entrance exam.

No you can't. Try for private universities such as Manipal or VGU, Jaipur.

Well, being a bio student you cannot opt for an IIT to study B.Tech as IIT admission is strictly on the basis of JEE scores. Though, there are colleges like:
1. SRM.
2. LPU.
3. DY Patil and some state colleges those offer B.Tech/BE biotechnology to bio students as well.

It doesn't depend on quantity but it depends on quality of study done in that time. You must make most use of your time. Some study for 5 hours and crack JEE and some more than 18 hours. So, you should study with full concentration in your study time.

At the time of filling application form of IITJEE, you are asked to set the medium of question paper. So, you can set it as Hindi.

MS in Germany will give you an International university exposure which will help you to build international career. I am of the opinion that if you are targeting international career, you may prefer MS in Germany over MTech at IIT.