So ...

Upon activation, go to Settings => MimeType Icons to access the plugin configuration page:

And it's ridiculously easy ... Simply select the icon size, an image format (PNG or GIF) and the icon alignment. Then check the checkboxes for any file type you want to use and you are good to go ...

Below, under "Advanced Settings" you'll find an option that will allow you to display even the file size ... By default, it's turned off because if you are using big files, it could be resource intensive. You can enable it if you want, just don't forget to enable the "Cache retrieved file sizes" option too.

Now let's see the result ...