Class 11

I will prefer CBSE as the study load is slightly less as compared to ISC and the quality of questions asked in the exam is better than the state board papers, thereby, aiding JEE preparation.

There is no particular stream to be taken for becoming a lawyer even science stream people can join LLB. But in my point of view, if you want to become a corporate lawyer then you should choose commerce stream.
If you want to practice in court (litigation) then you should choose arts.
Choosing these streams according to what you want to become will give you in depth knowledge about each subject and enhance your skill efficiently.
All the best.

You can become a nutritionist if you have studied physics /chemistry /biology /home-Science or any two combinations of subjects till your 12th class.

Hello manish,
As per your rank, chances of getting a government colleges is very slim for you. However, you may check here:
https://www.resonance.ac.in/reso/news/JEE-Main-Branch-Predictor.aspx

Choose PCM with English and IT .

You must target for IIT-JEE, IITs are best known institutes if you want to work in research field in physics-optics. After B.Tech you can go for MS-PhD from good US university to further carry your research work.
You must target IIT-JEE to get into top engineering colleges like NITs, BITs, VIT apart from IITs.

PCM with computers is what you should choose.