Caching

Can someone shed some light on how caching works in Keel?  I wish to use the
cache service in my custom app-xyz.  I would also like it if my Object were
refreshable using the Refreshable interface.  How can I create these
refreshable objects in my app and put them in a cache? 

Also, how do I configure the cache on the DefaultPersistence mechanism?  I see
that in the code "This functionality can be controlled with the "dbCache"
property in the properties file(s)".  Which properties file is that,
system.xconf?  

Thank you so much Keelers.  Your work and help has been very much appreciated. 
-Nathan