MBA Entrance Exam

Yes, you can appear for NMAT exam.

Self study is all that matters ! I would suggest you that - write a mock CAT to figure out your strengths and weak areas. Depending on your score you can figure out when to start preparing. Its possible to score well in CAT by preparing rigorously for 4-5 months if your basics are good.
Know more about CAT on :
https://edudrona.com/common-admission-test-cat/#1464927769900-a0617f54-da37/?mref=tanu

Hi,
These are some of the best institutes which offer CAT coaching :
1.Career Launcher
2. IMS
3. TIME
4. Bulls Eye
5. PT Education
They offer excellent coaching for CAT in India.

No, it is not at all necessary. Self study is all that matters. But take mock tets daily. Here are some good books which can be used for CAT preparation :
1.How to prepare for Data Interpretation for the CAT   TMH / Arun Sharma
2.Pearson Guide to Quantitative Aptitude and Data Intrepretation for CAT by Nishit Sinha
3.Quantum CAT by Sarvesh Verma
Know more about CAT on :
https://edudrona.com/common-admission-test-cat/#1464927769900-a0617f54-da37/?mref=tanu

You need to talk to the college once.
I'm not exactly aware of the fact

Here're the best colleges through MAT & CMAT:
MAT Colleges:
SCMS Cochin,
MS Ramaiah Bangalore,
Alliance Bangalore,ICFAIUPES Dehradun
CMAT Colleges:
IFIM Business School, Bangalore
Christ College, Bangalore,
UPES Dehradoon
Jaipuria Institute of Management, Lucknow
PSG Institute of Management, Coimbatore

PGPM stands for Post Graduate Programme in Management.Its a value added feature which is given along with the MBA degree.Its aim is to give maximum industrial exposure to the students.More than 60 percentile is required. IBMR Gurgaon is best among all,It is known for its placements and many certification courses.

you should focus on basic maths, English and on current affairs