Welcome to the world of jbpm :-).
We can store the process defitions directly in the db, which is essentially the content of PAR file. So you do not need to put the PAR file (I don't do it).
There is a set of extensible services that will help you query database for everything related to processes.
All the process related information is eventually stored in database, I am not aware of any other mechanism of storing the information.
hope this answers some of your questions..