Printing a document without first launching the app that created it is easy. Just select the document and use the Command-P keyboard shortcut (or go the the File menu and choose Print). The default app for the file's format will launch, and in most cases will send the document to your default printer without any interaction.
Applications that expect more user input before printing, like professional design apps, will wait for you to configure your print settings before putting ink on paper. It adds back in an extra step, but for file formats that default to Preview, it's as simple as select-and-print.