To change your picture, go to control panel - users - change picture.
I'm not sure what you are looking for regarding a picture hovering over docs, but..
Go to Control Panel - Folder options, view tab
-uncheck always show icons, never thumbnails
-uncheck display file icon on thumbnails
-check show preview handlers in preview pane
If the file view behavior is completely out of whack, you can click on 'restore defaults'