How should multiple (related) projects be arranged (structured) and configured so that they can share code, have a related package structure and enable proper unittesting, and ensuring no namespace collisions

[alisonken1]

As to the question "fail to see how version control relates to
code/test separation", the original poster asked several questions, one
of which was production/testing code separation.

Along with the separation (so while you're testing new functionality,
you don't break production files), a properly setup CVS allows you to
do this by importing files from a production branch into your testing
branch so you can re-use vetted code (production) in your trial code
(testing) without affecting what's already out there (inadvertently
breaking currently shipping code to customers).