IIT

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.

In any way you would have to study yourself. A teacher will only show you the path. It is you, who will walk. If you can prepare it yourself then there is no need of wasting your time elsewhere but if you need help then you must join. You should ask yourself, what is your need?

Both are nearly same.It only depends on student potential to be placed and to get good packages.

Dear Harshit,
It is ok that you haven't studied class 11th properly but I think you have realized the same. You have immense power that you can change the scenario. See you changed, you have realized. Friends often tease but use that teasing as your power to prove that even after 11th, I can crack IIT.
You know it is never late. You start first. Remember one thing, things become difficult because we don't dare. So, harshit take a deep breath and dare to change.
A very good luck.