Ph.D

The eligibility criteria for PhD in major universities is MA in the relevant discipline from a recognized university/institution with 60% marks in aggregate or equivalent and BA with minimum 60% marks and NET qualified. However, some university allows even students with 55% in MA. Therefore, you may do PhD in universities where you meet the admission criteria.

I have shared below the complete details about your query.
http://csirhrdg.res.in/jrfsrfra2.htm

Please refer to attached link for list of university which allows CA to pursue PhD:
http://resource.cdn.icai.org/26417bos15829.pdf

Yes why not. However, you must have completed PG.

Delhi University, Bombay University and ISB Hyderabad are one of the best for PhD in India.

MBA and PhD in the same college is a rare possibility. Please do not constrict yourself to a single city. MBA is all about exposure and practical learning, it's always preferable to move out to different state or city. You have AMmity University in Delhi which provides such course and also ISB Hyderabad.

Hello,
Thanks for Asking. Yes, you can go for M.Sc. or Ph.D. or dual course after completing your B.E. You can pursue M.Sc. from IIT's or IISC. To get admission in IITs, you have to clear its Entrance Exam - IIT JAM.
Click here to Know more about IIT JAM Physics - https://www.youtube.com/watch?v=4SBAhhto08M
I hope it will help you.
Best of Luck.