CBSE 12th

Hi,
Admissions will be a challenge with this percentage in Canada. You should try in other countries, check options in Australia, Italy, Poland, etc.

Ofcourse, you are elegible for MCA. You can apply.

Any B.Sc course is not best. It's your own choice to choose a course and make it best. But if you want to join any B.Sc course then bio chemistry, forensic science, forestry, genetics and B.Sc chemistry are good.

You will surely get a call for marketing but not for HRM.

Follow the link below for details:
https://www.shiksha.com/b-tech/course/b-tech-in-information-technology-college-of-engineering-anna-university-ceg-guindy-guindy-chennai-167421

Not after the result but you can apply to colleges after your board exams end.

Polytechnic after 10th can be good as you can get direct second year entry into engineering colleges through the LEET exam. But, I would prefer you to go with regular 11th and 12th because it will give you better options for appearing in engineering entrance exams.
Hence, if you plan to pursue engineering in the future, then go for regular 11th & 12th otherwise opt for Polytechnic.