1. To know which apps are running / open in background, move your mouse to the extreme, upper, left corner of the screen until you see a thumbnail of your running app. Right-click on the thumbnail and click Close.
2. To minimize just press window key to reach start menu or window+D to reach desktop
3. To switch between metro apps press window+tab
4. Google before you post
Humm...
I am aware of the Shortcut keys ! But the question is why on earth should I use a shortcut key to do things ?? Why I simply cannot use my mouse instead.
The mouse gestures are not responsive at all, even if I take my mouse pointer towards the left the sidebar or whatever it is called never comes out with the running apps listed.
Its not easy to use with Mouse and Keyboard.
I needn't google for everything like you !! Or you should have asked Microsoft to include GOOGLE as HELP for Windows 8