Diploma

Hi,
For civil engineering you may check Australia, Canada, Singapore, UK, US to name a few. Narrow down your choice based on admission requirements which differ, your budget, climate preferences, etc.

Dear,
If you have an interest in psychology then you should pursue Bachelors degree in the same. Degree will help you to go for further education, growth, knowledge, etc.
If you just want to check this field then, you can opt for the short term online certification in the same.
All the best>

If it is a 3-years state Polytechnic Diploma approved by state board of technical education and approved by AICTE, you can. As far as I know, any AICTE approved institutes do not offer Diploma in software application.

You can join any company in your core field or some job oriented course and you can also study mechanical engineering for further study by lateral entry.