You can easily add dividers to your nav links with an empty list item and a simple class. Just add the appropriate class to <li> elements between links. Dividers will be horizontal to start, but at resolutions above 768px they become vertical with the navigation.
Add .navbar-fixed-top and remember to account for the hidden area underneath it by adding at least 40px padding to the <body>. Be sure to add this after the core Bootstrap CSS and before the optional responsive CSS.