B.Com

No, I wouldn't say, it is a good rank. But, you have a chance to get an IPU college like Chandraprabhu Jain College or Institute of Innovation in Technology & Management.

If you have above 80% marks in class 12th, so you can get direct admission in B.Com. But, if you have not, so you have to attend entrance exam. The pattern of B.Com entrance is -
1. Verbal reasoning
2. Non-verbal reasoning
3. Quantitative aptitude
4. English language & compression
5. GK

No, it is not possible, if you don't have any reservations.

Yes, you can. Try to clear the levels one by one. I have seen 90% students are not able to clear CA Finals. Keep going from the 1st year of B.Com and grasp the concepts well.

Both of the courses provide us job, but immediate high post/salaried job is hard to get in India (excluding BCA if it is pursued from a high ranked/well reputed (for providing jobs) institute).

MBA in Finance must be your option, as you are a B.Com graduate. You can also change your field according to your new interests.

With 90.6% you can't get in Delhi College of Arts and Commerce for pursuing B.Com(Hons.) but don't lose hope you can apply for various off-campus colleges in Delhi University as well as some South campus colleges.