GMAT

GMAT tests your aptitude rigorously as compared to CAT. So getting a good score self is a big thing. Coming to the college part, for sure you can but except few institutes (I refer here to the colleges out of India.)

GMAT is a premier admission test for management program. 75% score and above will provide you a good opportunity.

Yes, GMAT score is acceptable, and you must score minimum 50-60% marks.

You have not mentioned where do you want to apply. You may please reframe your question and reraise it on the platform for an appropriate we expert to reply.

You can always check on the internet for available coaching and examination centers for GMAT examination. But you must not forget to maintain consistency in your academic performance in BBA for getting a good college.

You are not eligible to seek admission in MBA unless you complete graduation degree with min 50% from a recognised university.

It depends on what is your aim. If you want to apply for MBA abroad or ISB-Hyderabad then GMAT is mandatory and ISB, as well as institutes abroad, accept an only candidate with some work experience for ISB it goes to around 3 years experience and good colleges abroad around 6 years. Accordingly, you should decide.