B.A

Hi,
It depends on your interest, where you want to see yourself in the coming years. It can be directing films, photography, anchoring, journalist, event planner or in advertising and public relation.
According to name suggested above, you can opt one and go for specialization in particular area or you can go for Masters in journalism and mass communication for a recognized organization.

You have completed BA degree from Nagaland University, so you are eligible for hotel management course. Those candidates who have completed class 12th from recognized board are eligible for hotel management course.
Your age should be above 22 years. You can apply for Diploma course or graduation course. The duration of Diploma course is 2 years. The duration of graduation course is 3 years.

You can pursue it from Institute of Mechanical Engineers, India along with your job.

You can pursue B.Ed or MA in English for better career prospects.

Yes, it is very nice to pursue interior designing course along with BA in economics. But, you should be sure about your interest. If you don't have interest in doing design then you should not do this.

Yes, you can pursue M.Sc in economics.

Please mention your academic background and the course you are interested in pursuing.

Nothing different, you can go through normal procedure by applying various MBA entrance exams.

Since, you have tagged science, so you must choose B.Sc as it is a good option.