Commerce

You can appear for government exams along with a job and while doing an internship also. It doesn't matter as you need to be prepared for those exams to write them.

That depends on what you want to do. If you want to pursue your future in commerce only, for eg. CA, B.Com BBA, etc. opt for Maths instead of physical education and Economics Instead of Entrepreneurship (if your school has that). But if you want to do something different like LLB, Hotel Management, then opt for anything you find easy. Accountancy, Business Studies and English are mandatory (at least was in my school).

There is no cutoff in schools. You just need to score passing marks/percentage i.e, i guess 33% marks.

Both have good job opportunities.
It totally depends upon your interest.
My advice for you is to go for commerce stream.

Yes, you can pursue Bachelors in law after completing class 12th in commerce.

Hello,
You can pursue BCA.
Thank you.

Yes work experience will help you understand concepts better and will/will not impact placements as it is based on other criteria as well.