Indian Institute of Technology, IIT Bombay

No, this year IIT declared that no marks of class 12th should be taken into consideration while deciding JEE Mains and Advanced merit, but 75% in class 12th is compulsory for filling JEE Mains form. Below that you are not able to apply for JEE Mains.

Hello Manish,
You may refer the link below for the list of top computer science engineering colleges in Maharashtra:
https://www.shiksha.com/b-tech/ranking/top-computer-science-engineering-colleges-in-maharashtra/46-2-114-0-0

Hello Vivek!
The admission Into IIT Bombay for undergraduate programs is based on your all India rank in JEE Advanced examination.
The total marks in JEE Advanced varies every year.
So your AIR should be at least below 1000 to get a seat at IIT Bombay for any course.
You also need to clear JEE main to get qualified for JEE Advanced.

Metallurgy is a very niche engineering branch and one don't get a very high starting package. So, after completing metallurgy from IIT Bombay, you can expect a package of 4.5 to 6 lakhs per annum.

Admission for M.Sc-PhD Environmental Science and Engineering is offered through JAM with following test papers: Biotechnology/ Chemistry/ Mathematics/ Physics . If you can clear JAM after BCA you can seek admission in Sc-PhD Environmental Science and Engineering.