MBA Scope

It depends on your interest and institute's placement record.

The major benefit you get from these countries is tuition fee, which is comparatively lower than other countries like UK, USA, etc. But, the major constraint is the language. Germany is a much better option as you are from mechanical background.

You should aim at older IIMs (Bangalore, Indore, Lucknow and Calcutta) and then the newer ones. Other colleges you can look for are MDI-Gurgaon, NITIE (good for engineers), S. P. Jain, NMIMS-Mumbai and IMT-Ghaziabad.

Most of the universities include language marks for grading.

Being an engineer, you can opt for any of the specialisations among Operations / IT/ Systems/ Marketing/ International Business (IB). It purely depends upon where your interests lie. And all are considered equally rewarding specialisations, specially if done from the best B-schools as the top companies prefer these schools first.
I hope it helps.

You can go for a job to gain some experience, and then according to your field, you can go for MBA.

K.J.Somaiya is one of the leading colleges in Mumbai when it comes to placements. The average CTC ranges between 8-9 LPA. Maximum students get placed in the placement weeks itself. At par with K.J.somaiya is Welingkar college, Mumbai. Welingkar also has good placement assistance.

I would advise you not to leave your job. Remote location of your current job can be converted into an advantage to build your career. You have plenty of time available to prepare for entrance examinations in remote areas. You may use this time to prepare and crack higher education entrance examinations.

The job opportunities will depend on your specialization in MBA. If you have taken finance, then you could join investment banking or equity research area. In case you have taken marketing, then the field is wide open for you and join any industry in the sales domain.
However, keeping in mind your B.Tech qualification, you could join larger Indian/ MNC companies, who operate in the relevant areas and be a part of the sales, marketing or product teams.

Jamia Millia Islamia has a good reputation. It does have a placement cell, but to get a good job thereafter, you would have to study hard.