Indian Institute of Technology, IIT Bombay

Hello Piyush,
Congrats for securing for a good rank in JEE Advance, if you have to choose between the above two options, definitely go for IIT Powai, for the reputation and also you can change branch after you score decent in first year.
All the Best!

Yes, it is best for petroleum engineering. You can check it by yourself here –
http://www.indiaeducation.net/careercenter/engineering/petroleumengineering/

UPES rank is 3rd in terms of petroleum engineering. 1st is IIT, Bombay and 2nd ISM, Dhanbad.
You can check the ranking here –
http://www.indiaeducation.net/careercenter/engineering/petroleumengineering/

Hello Naveen,
There is no limit in the salary packages for the IIT graduates. Since mechanical engineering is one of the top branches in engineering, the salary packages will be really huge. And it also varies every year with the talent of the graduates (IIT)
The average package will be Rs. 5-10 lakhs per annum and the maximum package may go upto Rs. 20-30 lakhs per annum or even more higher depending on the student .
The highest ever package offered at IITs (IIT Kanpur) was Rs. 1.34 crores per annum by Microsoft, but I'm not sure about the branch (may be CSE).

Hello Harsh,
These are the best two in India. Prospects are best here after passing out than anywhere in India. DRDO, ISRO, Armed Forces and some public or private companies also are recruiters.

Kindly refer to the link mentioned below:
http://www.bestmal.com/best-books-iit-jee-chemistry/