MBA Entrance Exam

Yeah, you will get some relaxation as you belong to the reserved category.

Start now by solving 5 - 10 quants every day and read newspapers every day to make your vocabulary strong.
When you get into the 3rd year, start your full-fledged preparation by joining classes or solving mock tests.

You should prepare for CAT exam. If you prepare for CAT, you can easily qualify MAT as CaT is tougher than MAT.

Yes you can, provided you also have a valid score from CAT / XAT / GMAT / GRE.

As you have experience of almost 3 years you can pursue E-MBA and to get admission in top B-Schools, you have to give CAT or XAT exam to get admission in this course. Also some top universities conduct separate exams for this course. Otherwise fro normal MBA you have to clear CAT, XAT, GMAT and other exams conducted separately by universities.

Please refer to the exam websites for this query. Reservations vary for different exams.

Yes, you can join classes there. There might be some centres of TIME or CL. However, classes only provide the baseline for CAT preparation. Rest is completely your own hard work.
All the best.

Minimum 50% is essential to appear for the exam. Though all good colleges prefer a criteria of 60% graduation score.