Also, wouldn't it be preferable to have "firstboot" (if
that is what
it is called now) skip the user creation dialog if a user was
created during the install?
Yes, that is the plan, but it's not implemented yet.
Firstboot is dead now, the new tools are called initial-setup and gnome-initial-setup
(yes, there are two of them, it's another loads of fun we need to deal with).