>Excess terminology
Agreed. Except that I don't think Excerpt is terminology used by Drupal core. BTW the term "trimmed post" was probably added because newbies complained they didn't know what a teaser was.

>Confusing terminology
Have you got any better suggestions for "page", "story", "term" ...
(If so then post them to the issues queue http://drupal.org/project/issues/drupal)