In this video Joe Shindelar covers the important changes coming to theming with Drupal 7. He starts off covering the basic concepts of Drupal theming, and then dives into the changes to each of the three pillars of theming: the .info file, the template files (tpl.php), and template.php. During the course of this discussion and demonstration you will see the new Drupal 7 core themes, get an explanation of the brand new rendering system, as well as get the nitty grit on things like new templates and variables. The video also shows how to upgrade Drupal 6 themes to Drupal 7, with lots of tips and tricks. It wraps up with a question and answer period with the whole Lullabot crew.
If you'd like to theme the pager then you'll want to take a look at overriding the theme_pager() function.
If you want to grab something from the node content and print it somewhere in the page do something like this:
If you want another great resource go watch Moshe Weitzman's video from Drupalcon SF: http://sf2010.drupal.org/conference/sessions/page-render-drill-down-drup...