CBSE 12th

Go for DU, AMU or JNU.

B.pharma, B.Tech in biotechnology, B.Sc in biotechnology, B.Sc in microbiology, B.Sc in forensic science, etc.
Good luck.

You can pursue B.Tech in computer science and B.Tech in any field you want but I would suggest civil, mechanical and computer science.
You can do BCA also.
Good luck.

Yes, the line you want to choose and it is different for different boards.

Hi,
Please go through the below college predictor you will get to know the details about it.
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

Try NIIT, Amity and LPU. Actually there are many pvt. colleges that consider 12th marks for eligibility criteria. And if you have appeared for JE and you think your rank is low that doesn't mean you can't get any college. But one thing that is for sure is you will not get any govt. college.

No, it's not mandatory.

To join Canada, you need to do a 4 years degree course. You should do graduation in the field where you want to pursue Masters. Remember, if your UG background does not match with your PG subject in Canada you may be rejected. After completing graduation, do a related PG degree or a university PG Diploma.