Re:Why I’m uninstalling Windows 8
by contextfree on Tuesday August 21, 2012 @09:10PM
(#4415632)
Apps with background tasks are generally supposed to pop up a notification when they're done (the APIs for the new notification popups are available for use by desktop apps too btw, although admittedly they probably won't be widely implemented for a while if ever).
And apps can be suspended or closed. Suspended is something like 'sleep mode'. They're still in your alt-tab menu (you can directly launch them).
And regarding the last question: yes: metro is the default. When you boot up Windows you will see metro. And as far as I know there is no longer the option to remove it. Every time you need something you will return back to the metro start screen.