Computer Science and Engineering

Check for some private colleges, they might have vacant seats. You have option of making one more effort for IIT-JEE exam.

Don't worry about that, you will surely get a good college. First of all you will need to clear all your papers and should not have any active backs. After that you can apply for lateral entry admission process and face the entrance exam, PI etc. to get into another college.

Australia is indeed a very good option to pursue Masters. Also, job opportunities are great in Australia.

Go through the below mentioned link :
https://www.toppr.com/bytes/top-private-engineering-colleges/

Try to get admission in IITs/NITs for B.Tech. As you studied PCM and computers and you have interest in aircraft you can look for aeronautical engineering (it is there in IIT-B and some NITs). After that a Masters degree is good to enhance your skills as aircraft needs quality skills.

Below mentioned are the top colleges for computer science engineering in Canada:
1. University of British Columbia.
2. University of Waterloo.
3. University of Alberta.
4. Simon Fraser University.
5. McGill University.

Chances of a good payment always depend on you. First of all, polish yourself in one or two technologies, then get started with any job you get. Meanwhile, keep applying for better jobs and switch. Don't wait to get a good one at the first go.
All the best.

Currently CSE graduates has best opportunities and good chances of high salary jobs but it is very rapidly loosing it's prime position. In next few years it will have similar scope in comparison with core branches of engineering.

To get admission in US universities, first you have to clear some exam like GRE and TOEFL. After clearing the exams, you can get admission.

Currently job opportunities in computer Science field are very high. Based on scope and opportunities MS in CSE is better option over MS in civil engineering.