Delhi University (DU)

GGSIPU and it's affiliated institutes are very good option for degree course if you are unable to make it to DU. You can also evaluate Ambedkar University or Amity University for studies.

Yes, for Delhi University regulations mathematics is compulsory at class 12th to pursue BMS course. But, it depends upon university to university. You can check another university, if you want to pursue BMS.
All the best.

Today, cut off for commerce stream is very high in Delhi University. With this percentage you may get admission in other colleges of Delhi University but you have little chances in SRCC. You can check for cut offs regularly. The cut off of SRCC starts from 99 and 100. You have to check, otherwise, you can get admission in other DU's reputed colleges in 3rd or 4th cut off list.

Delhi University (DU) does not offer MBA by distance learning. DU offers full time and weekend MBA degree courses.

Yes, you can. Your 12th marks with good percentage is enough.

Yes, you have chances to get admission in DU after getting more than 90%. The cut off is very high which is almost 99% in DU, but you can get chance either in first, second or third cut off. It totally depends on the CBSE results.

Yes, you can opt for PhD abroad. There are so many opportunities available for you.