Accounting & Commerce

You have to check with the college for that as they define their own regulations.

Valuable work experience from good company is always an advantage (after B.Com). Plan to pursue MBA after 3 to 4 years of work experience. With more than 5 year of work experience, MBA may be an option for you. In either case, after MBA, you will have better opportunities in different companies. Follow https://shiksha.com to know more about colleges and its ranking.

You should complete your Diploma, you will eligible for both the courses.

Hi,
The percentage and university always effect the career. If you are applying for a government job, then the recruitment organization always over look on your career and university but private organization always select those, who have talent.

You should do the graduation first like B.Com or BBA. Then, you should give the exams of government exams also. There are many exams for government job. You should try that and you will get good government jobs if you score well.

If you have any specific interest, then follow it. If you don't, and you have the luxury to choose then opt for Science as you can switch later on depending on your interest if it changes.

You should not think about CA, if you have done BBA. It is better to pursue MBA after completion your BBA.
Why you want to waste your time in such a difficult course, while you have an opportunity to take an easier task i.e. MBA.