My customer wants to host a web site for public access and to allow the web developer to remotely upload the site and be able to do ongoing updates. As I understand it, this needs to go into the primary i-bay ...
No, that is not true. A different i-bay can be used to provide the website content for the primary domain. I don't think this can be done via server-manager, however.
From the 'root' user command line, do:
/sbin/e-smith/db domains setprop your.domain.name Content ibayX
/sbin/e-smith/signal-event domain-modify your.domain.name
Then have your web developer update ibayX via SCP.