Australia

Here is a link with some helpful information for you:
https://www.studyinaustralia.gov.au/english/why-australia

Well, you will need to check if your credentials are valid in Australia or not.

Strictly no, as they consider credits of all subjects.

Yes, you can do your B.Tech from Australia after completing your Diploma from India.

When you study abroad, all Masters are specialised programme not as general computer science. Normally Masters in computer Science is a conversion programme for non-computer UG people to come to IT field. Hence, first, you decide what you are going to study and then look for universities. RMIT is one if the top universities. See the website and see the courses offered. Also, be aware of the cost. It will cost you 30 to 40 Lacs in Australia. You can do one year master in UK for just less than 29 Lacs.

Go for Symbiosis Institute of Management Studies, Khadki, Pune.
They charge 60K fees per year and it is one of the best institutes you can go for. Best of luck.

Private universities in Australia accept applications from students who have not more than 7 or 8 backlogs, but to be honest almost all high-profile private universities accept applications from students who have 4 backlogs. The Group of Eight or Go8 universities accept maximum 2 or 3 backlogs. If you want to opt outside the private ones, you are welcome to apply, provided you have 8 backlogs. Please note that the number of re-attempts in the exams will also be counted when you apply with a backlog history to a university in Australia.

Both have a good scope in terms of job, but you have to check whether the university course is ACS accredited or not and after that you can apply.

You can apply for master of management for engineers in Central queensland university and you can also apply for elicos leading to master degree in other universities.

Australia is the best option for you. You can get a good job there.