IIT

On the basis of salary and alumni network. All the 7 iits are about 30 to 40 years old so you can think how much strong is the alumni network and some recruiters in the iits are the passout students from IIT who started up their own company and came there for recruitment.

Definitely yes mit is far better than all the iits as it has so much alumni network and research options you can think like that IIT has about 40 to 50 % quality than mit.

After 12 you have many options but as you know majority choose engineering or doctors. If you have chosen maths in class 12 then you have to give engineering entrance exam I. e IIT JEE. First you have to give JEE Mains and if you qualify JEE Mains then you have to give JEE Advanced. You will get admission in NIT on the basis of your JEE Mains performance and in IIT on the basis of your JEE Advanced performance. So all the best for your exam first focus on JEE Mains because it is quite easier than JEE Advanced so try to crack JEE Mains then think for advanced.

Simply graduating in aerospace/aeronautics etc. May not be enough, you might have to study further and go into research in a big way, M.Tech and Ph.D. would lead you to these organisations depending upon your research area. Pursuing these programs from ordinary colleges will not be enough, you will have to do these from top universities/colleges of high repute like LPU. DVD.