The page has been replaced by documentation in oi-userland: https://github.com/OpenIndiana/oi-userland/blob/oi/hipster/doc/makefile-targets.txt and https://github.com/OpenIndiana/oi-userland/blob/oi/hipster/doc/makefile-variables.txt
You should not need to use root privileges to run any userland operations. If something only appears to work because you're running as root, there's a good chance that something's broken that isn't being fixed by hammering it with privileges. If in doubt, please mail to firstname.lastname@example.org or reach us on IRC.
REQUIRED_PACKAGES tries to guess build dependencies and adds this information into component's Makefile. Usually, contributor should double check and add any missing package.
Actions are the conventional steps that are used for targets, which can be replaced or extended to deal with individual components. Their names should make self-evident what they do: allow additional actions to be performed before the main activity of configure, build, install or test. The below provides a few tips and tricks as examples.