Dear Manoj,
Regarding the Institute, Please go through my Blog.
http://scn.sap.com/community/career-center/blog/2015/08/13/best-institute-for-sap-training
If you think, you will get job after certification easily then you are wrong.
Certification adds value but there is no job guarantee.
Opportunities in PP is less compared to SD,MM & FI. However if you have PP Business Knowledge and your passion is PP then go for it.
Learn SAP well and gather as much knowledge as possible and practise in Demo system daily and apply for jobs but never leave your current job untill you get a new job because getting a job for a fresher in SAP is difficult.
All the Best.
Regards
Shaik