Aeronautical Engineering

Few colleges in Maharashtra that have Aeronautical Engineering are:
Indian Institute of Technology- Bombay
GuruGram Institute of Aeronautical Engineering
Indian Institute for Aeronautical Engineering
Priyadarshini college of Engineering

You may evaluate private universities for doing BTech Aeronautical Engineering. Universities such as Manipal University, Amity university, Anna University are also good options for BTech Aeronautical Engineering. You may refer to following link for list of top Aeronautical Engineering colleges in India: https://www.shiksha.com/b-tech/ranking/top-aeronautical-engineering-colleges-in-india/49-2-0-0-0

Yes, you are looking for a right way. It is good to pursue maintenance engineering as the scope of the aircraft industry is enhanced during last years.

Mechanical engineering is best in B.Tech if you want to do aeronautical then you can go for mechanical for Bachelors and then aeronautical in Masters. You will have both the degree with two different courses.
All the best.

The JEE scores counted will be for current years exam. So, you have to appear again to crack the admission.

You are advised to appear for JEE Mains to qualify to appear for JEE Advanced to seek admission in aeronautical engineering at IITs. With JEE Mains & Advanced scores you can also seek admission in other prestigious engineering colleges such as IIST, PEC University which offer aeronautical engineering degree courses.

Follow the link for the same:
https://www.shiksha.com/b-tech/ranking/top-aeronautical-engineering-colleges-in-india/49-2-0-0-0

With a number of Automobile companies setting up manufacturing facilities in India, Automobile engineers may do well. Life may be little tough for Aeronautical engineers (due to Flight Safety issues) but they do earn higher salaries. Select a branch as per your interest in that branch.

You are advised to target above 75% marks in 12th board. But your target should also be to crack Engineering Entrance Examinations such as JEE to get branch of your choice.

Hello Akshay,
As per dictionary, aerospace is the industry that produces aeronautical products. Else, both are identical. There is no other difference.
Best wishes!