Users... Wikipedia or Writeboard) as viewers only
Wikipedia) as viewers only
Installers: MediaWiki and come to install TWiki with very different assumptions
Administrators: People tasked with administering one or more TWiki installs. One of these may well be the person who did the installation.
Developers Dakar is far easier to install than Cairo, it still takes a pretty sophisticated set of skills to do so.
bin/configure can enable plugins.
Perl or Apache.