[Zope] New versions of a product

What is the best strategy to use when upgrading to a new version of a Zope Product that is already in production and has significant amounts of data in it? The issues are : 1. Modified hierarchy of objects 2. New classes/objects - not a problem as they don't exist in the earlier version. 3. Deleted classes/objects (i.e. no longer required) 4. Renamed classes/objects 5. New methods/attributes - not a problem as they don't exist in the earlier version. 6. Deleted methods/attributes (i.e. no longer required) 7. Renamed methods/attributes Robert Leftwich