Indian Institute of Technology, IIT Bombay

Hii Murali,
Hope you are doing good. I prefer that first, you solve all the previous year papers of JEE Advanced. Now, coming to reference books I prefer MTG for maths and HC Verma for physics. But I am really sorry to tell you that I don't remember the good reference books for chemistry. Also, please check with some more people regarding books.
Hope this helps you.

It seems that it is no possible as you have to give JEE Mains for entering into IITs after 10+2 as IITs don't entertain lateral entry admissions. So better try other good colleges.

Anything below 2000 will give you sure shot admission as some top performers choose CSE and IT in large numbers.

You have to secure under 100 rank for the department you have inquired about because it is the second most demanding branch after CS in IITB.

It depends on which stream and course you want to pursue as there is different rank for different courses like B.Tech, B.Sc, and other dual degree programs.

This link will help you to know more about the aerospace engineering offered by the IIT-Mumbai.
https://www.shiksha.com/college/department-of-aerospace-engineering-indian-institute-of-technology-bombay-powai-mumbai-54184/admission

Of course, IIT Bombay is far better than any college. Since, it is a government reputed college, we all know. It has everything that one dreams of. If one is getting admission in this college this means that your life has now get the direction for good future provided he/she perform well. It is better and have every facilities you need. Best of luck.

All are important in their respective field.
But, by seeing the growth I can say that the CS and IT industry are growing much faster.
Choose that field in which you have interest.
You should have goals to achieve, so basically choose the branch according to your interest only.
Scope of all branches are same, but slightly differ.
CS have very good scope and has various option. You will have and more opportunities in private sector only. But, not much than in government sector.
Whereas, civil has much scope in government area, rather than private area.
Electronic and mechanical have good scope in both private as well as Government sector.

NCERT books are best for JEE preparations.

First of all, you have to score above 80% in 12th. Then, you should crack JEE Mains and JEE Advanced with high scores. Get into the top spot in counselling and that's it.