How can I alter the HTML output of a specific content-type in display mode via a module, without creating the node type in a module? I have a specific node-type: resource. The default display of a resource node is not quite what I want, so I need to over ride the themeable output - so far so good. The problem is, I've created my resource node-type through the Drupal 7 GUI. How do I write a module that just over rides the HTML output for this one content-type?

...and, in piggyback to that question - I will have many other node-types that I've created through the GUI, but need custom output for. Is there a way to create just a single module that will handle the custom output for all of these types?

Thanks.
IMO, a very good approach would be using Display Suite to generate the basic markup/layout and then add the appropriate styling to the theme.