I like to advice you that don't start collecting information UNTIL you have a clear, defined foucus question, i.e. what exactly you like to find out. If you shift your focus question a little during the PIP-making process, all of your effort will be wasted. Ask your teacher about the appropriateness of your topic. Please don't tell him/her "I'm doing a dying religion". Consider what aspect of this religion would you like to find out about? How does it relate to Society and culture? How does this aspect contribute to your understanding in Society and Culture?
Good luck!