XAT

You can use The Times of India application, it will be beneficial for you.

Cutoff for CAT/XAT is 99.9X percentile

You need to study only 4 hours daily and try to assess your strength and weakness in the course of study. You need a good coaching, where you can get good teacher, which can meet your needs.

You can appear for exam like IIFT, I think in India no other college is as good as IIFT (Indian institute of foreign trade) for international business.

MAT is easy, but there are only 1 or 2 colleges, which accepts MAT score.
All the best.

It's your wish.
CAT, MAT, XAT, SNAP, and NMAT are few of them.
Almost all the colleges accept MAT except IIMs, Xavier's, Symbiosis, and NMIMS. You need to qualify entrance exams like CAT, XAT, SNAP, or NMAT to get admission in IIMs, Xavier's, Symbiosis and NMIMS.
MAT is enough if you wish to apply for other good colleges.

Yes, you can appear for national level management entrance exams, but even if you score good marks in the CAT, MAT or XAT exam, you won't get admission in any of the B-schools. You will have to clear your backlogs, first.

TIME Institution's study material notes are the best if you want to focus more on quantitative aptitude and data interpretation.