EBS Single Home (NAS) installation. Contents of the "Config" local directory structure

 We have implemented Oracle E-Business Suite on our Internal Web/Forms Server on a Single/Shared APPL_TOP.  I want to start a discussion on what the contents of the local Config directory structure is and the order of hierarchy of those files versus the one's in the original ORACLE_HOME or IAS_ORACLE_HOME. 

1.  The contents:

What is and/or should be contained within this directory structure?  Since the original files are not removed from the $IAS_ORACLE_HOME when they are created in the $IAS_CONFIG_HOME, which files are used. 

For example, I would like to update the jserv.properties file.  The file exists in BOTH the IAS_ORACLE_HOME and the IAS_CONFIG_HOME.  To make things more difficult, they have the same file timestamps.