GMAT

For Canada ILETS is important for MBA but for UK GMAT is compulsory.

It is in the January and at the end of November. You can also the same online on GATE's website.

Every year the cut-off changes. So, it is difficult to predict now.

See, these all are various entrance exam for either MBA or PGDM the difference is at their toughness and type of colleges offers.
Talking about CAT, this is the exam having highest toughness level but if you scored good percentile, then you will get IIMS and rest will provide B-schools.

Also, take a digital course study it fast and get to practice tests. Understand this thing that every year 1 lakh plus students give CAT and join classes, but only 5k makes it to IIM so self-study goes the long way.

Hi,
Yes, you are eligible to apply but much cannot be said about admissions since NTU is very selective and your grades are not too great. Please read here about the requirements:
http://www.nbs.ntu.edu.sg/Programmes/Graduate/NanyangMBA/Pages/Home.aspx

You need above 710 score in GMAT. If you are opting for GRE nothing less than 315 is what I would say.

If you are doing graduation degree from recognised university then you are eligible for CAT and other MBA examinations.

CAT score is accepted in a large number of B-Schools in India. Appearing in CAT is a better option in comparison to MAT & GMAT. If you targeting international B-Schools for MBA then you are advised to appear for GMAT. CDS is an excellent career choice.