To add icons for vimeo and youtube, you will need to create the png images corrosponding to each. You can take reference from say fb icon's image i.e., in Current/images/fb.png or the other social media icons that are there already.
You will also need to add a bit of css for each new icon. You can look for .linkedin or .aim in the Current/css/style.css file and simply copy the css and replace it by the new class name i.e., .vimeo and .youtube and also update the path to the images for vimeo and youtube.
To make the link open in the new window, simply add target="_blank" in the "a" tag in the above code. e.g.