B.Sc Physics

First, decide the university from which you want to study and country were you can go. You should be ready with your passport and visa. You can check the previous record of that institutions.

Yes, you have the physics background, and for aerospace, physics is recommended. Score well in IELTS and GRE exam, and draft a good SOP.

Hello Adwaith,
That depends on your ability to grasp things.
S.Chand publishing books authored by Brijlal and Subramaniam is a very simple book and anyone can understand. If you are looking for advanced or in detail of a particular topic, I would recommend you to refer foreign author books.
1) Sears and Salinger, Thermodynamics, Kinetic Theory and Statistical Thermodynamics.
2) C Kittel and H Kromer - Thermal physics.
3) Advanced engineering mathematics - Erwin Kreyzig 5th Edition, Wiley Eastern Ltd.
4) RPFeynman, RBLeighton and M Sands - The Feynman Lectures on Physics, Volumes 1 & 1, Narosa Publishing House, 1998.
All the best.

For civilian ATC controller, you need M.Sc or B.Tech.
For more information, you can visit the below mentioned link:
http://www.atcguild.com/jobrqrmnt.asp
To become ATC controller in IAF (or a Fighter controller), you have to write AFCAT exam with B.Sc or B.Tech and join admin branch initially and then try for ATC / FC.
You can refer to the below mentioned links:
http://careerairforce.nic.in/
& http://www.nausena-bharti.nic.in/

You have to calculate your PCM marks only, but some colleges include English also. So, I would advice you to go through college's website in which you want to get admission.

Hello,
After completing B.Sc. you have many options available.
You can go for Jobs (in government field also like - IBPS PO, SSC CGL)
You can go for further studies like - MBA or M.Sc.
If you want to continue your studies then you have a best option available to do M.Sc. from IIT's or IISC.
For that you have to apply for IIT JAM.
Click here to know more about IIT JAM - https://youtu.be/4SBAhhto08M
I hope it will help you.

You have complete B.sc in Physics so you can go with following field -- Life-Science professions such as medicine, pharmacy and some other good field like- geo-sciences, engineering, architecture, computer-related programs, environmental studies, technicians, Science educators.
you are eligible for
Union Public Service Commission for Posts like IPS , IAS , IFS
Staff Selection Commission
Indian Forest Services
Banking Sector
State PCS
Indian Defense services
etc.