Hi, Carri. I'd say that a technical writer generally would not have to
build and manage the site. But the tech writer should know what conent
management system is being used and a little bit about how it works.
You'd especially want to know how the CMS integrates with your
authoring and publishing processes (if at all) and whether it has
metadata capabilities that you could use to make your content easier
to search.
Hope that helps.
Larry Kunz