1. The application menu bar appears across the top and changes depending on which application currently has the focus
  2. Applications that need to be manually installed can be picked up and dragged to the Applications folder after you open open up the delivered disk image
  3. If you have an Mighty Mouse (the mouse that looks like a bar of soap), you can enable multiple mouse buttons in System Preferences
  4. You can change the format of the dock (make is smaller and switch on the magnification affect) in system preferences
  5. If you have one button mouse, then you can use the second button by using the Ctrl key as a modifier
(With big thanks to Kirrily for pointing out my cock up about modifiers)