Is Project Manufacturing Required with Inventory?

R12.1.3  My client is planning to implement Inventory into an existing Project Centric environment. They use many Projects modules, but have not implemented Project Manufacturing.

It is my understanding that in order to hold Project stock in a subinventory, Project Manufacturing is also required.  Is this correct?

They want to track the items they bought through Purchasing but instead of expensing directly to the project, they need to track the items in the warehouse until they are issued to that project, and will therefore place them into Project locators.

The second level of confusion is they are looking to implement Project Procurement and soemone told them that if they do, they do not need Project Manufacturing. I do not believe that is correct but would appreciate verification.