New Zealand

B.Tech in computer science has better scope.

If your degree is accredited by UGC/AICTE, then your MCA degree is valid.

Hi Anshul,
Please go through this page to get a clear understand about the PG Diploma courses in New Zealand
http://www.nzqa.govt.nz/studying-in-new-zealand/understand-nz-quals/postgraduate-diploma/
These are job-oriented and very useful. However, much can't be said about its value in India. Most PG Diploma courses can lead to MS degrees, it is better you look for such programs to work in India. You should also gain valuable work experience via the post study work permit.

If you are well qualified you need not necessarily do a course. But pursuing a full time course in the country abroad gives you certain benefits such as degree recognition, post study work permit, PR options etc. English proficiency tests like TOEFL or IELTS are also required. Study as per your career plans. You will know the kind of jobs you are looking for. For more information on jobs you must refer to job portals. I don't think you will find job vacancy information here.

Taking admission there will be very difficult as the percentage is quite low. You might get admission in a small institute however the biggest concern would be the VISA as it is actually a challenge to get VISA at this percentage.

USA - varies 30L to 40L
New Zealand - varies 20L to 22L
Germany - varies 13L to 15L

Canada have better prospect for mechanical engineers. But, only experience will not help you. Canada provide thousands mechanical engineers at their local soil, so if you prove yourself that you are better them, then you will get fruitful result.
All the best.

You can apply for Australia under ELICOS.