Delhi

Kolkata too has good faculties and institutions for your support. Delhi would have an advantage of being the capital city.

It is a premier place to learn English in the globally acknowledge manner. British Council, other than conducting workshops and special training offers formal courses as well:
https://www.britishcouncil.in/english/schools/Delhi
For adults:
English:
Spoken English for IELTS (Regular)
English for IELTS (Intensive)
Introduction to Creative Writing
Business Communication Skills
Cambridge CELTA
Masterclass for IELTS Trainers
For young learners:
Summer School (7 to 17 years)
Primary and Secondary (7 to 14 years)
Upper Secondary (15 to 17 years)

Hello Adarsh,
It's nice to see your dream of becoming an aeronautical engineer. Apparently this school has campus in Neemrana as well as Palam Extension. I am attaching a link that will give you all the required information. Better hurry up since entrance exam is in May. http://www.soadelhi.com/

Both cities are educational hub. It depends on your selection and other factors. All the best.

Pursue MA in English from Best Colleges of Delhi as per cuttoff. Read relevant information on Website. Take decision accordingly. Relax.

Though it is tough to get into BVIMR, but you can still opt for IMED Pune. It's also a top ranking institute under Bharati Vidyapeeth University with good placement opportunities. Do attend your counselling.

Yes, there are many. Kamala Nehru is one. You can search for other.
Please upvote.

You would qualify for most of the colleges for a course in English Hons. There are over 110 B.A. Colleges in Delhi. Please refer to the link provided below for a detailed list of these colleges. You should be able to navigate to a course and college of your choice using the filters on the web page. Regards. https://www.shiksha.com/humanities-social-sciences/colleges/b-a-colleges-delhi.

Vivekananda Institute of Professional Studies
Trinity Institute of Professional Studies
Fairfield Institute of Management and Technology.