How do I create diagrams, flowcharts, org charts, layouts, etc)?

Use Gliffy.  While editing a page in Confluence, type { to trigger the menu that leads you to the macro browser - open up the macro browser.  From there, you'll see a "Gliffy Diagram" option that brings up a UI that allows you to select a template and then manipulate objects to make a diagram.  Save it in Gliffy (file -> save), quit Gliffy (file -> close/exit) and you'll be back in your familiar "editing a page" mode. Documentation is found at the vendor's website:

http://www.gliffy.com/blog/user-manual/