I noticed ItemId passed with every method and I'm trying to figure out its purpose within DotNetNuke and if I can replace it.  I assume it's meant as the primary key to identify database record, similar to the old ID auto-incrementing field in every Access table?

I'm using an existing database with more meaningful primary keys like CustomerID and OrderNumber, etc.  What are the ramifications of me passing those around instead of ItemId?  Will I lose framework functionality (ie. security,collaboration, etc.)?   Also, some of my primary keys are varchars and a few are Guids.  Will this cause a problem?  

Restructuring the existing database is not an option.  Should I design a "mapping" layer for these arbitrary ItemIds to better fit within the DotNetNuke architecture?