CAT

You may try an online MBA program in which the scores are not necessary. Go to the official NIBM page and read through the courses offered. NIBM (National Institute of Business Management) offers one year MBA, two year MBA and one year Executive MBA in online mode. NIBM also offers online video tutorials to all its registered students. NIBM provides a wide range of specializations that are very flexible too.

As per its history and track record, TIME is the best option. You can also consider other institutes like Career Launcher and CAT King.

According to me, if you are living in Ahmedabad, then opt for Endeavor classes. It is the best coaching institute in Ahmedabad for the preparation of CAT exam. They provide you good study materials.

There are lots of B-schools which accept entrance exams other than CAT.

Generally, you need to score at least 110-120+ to secure 85+ percentile in CAT. This means you should get around 40-45 questions correct. So, it's not at all difficult to score that much, provided you're thorough with the basics & give the mocks properly.

Yes, you can apply for CAT.

You need to score minimum 50% to be eligible to CAT or MAT. You can take coaching or do self-study for CAT exam.