As it turns out, showing the history tab only to users with edit privileges was an easy modification. It simply required adding if "$this->mTitle->userCanEdit()" to the "if" statement on line 653 of skintemplate.php. The complete line now reads " if ( $this->mTitle->userCanEdit() && $this->mTitle->getArticleId() )"
The more daunting task is controlling who can edit, but that was handily resolved by installing GroupWiki from _http://sourceforge.net/projects/groupwiki_ (http://sourceforge.net/projects/groupwiki) .
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