string url = HttpContext.Current.Request.Uri.OriginalString;
TaxonomyNavigationContext class ontains several properties which will help you to work with friendly URLs programmatically,
For Example:
 HasFriendlyUrl and ResolvedDisplayUrl (all properties can be found here).
you can get friendly URL using the following code:

  string url = "";
if (TaxonomyNavigationContext.Current != null &&
     TaxonomyNavigationContext.Current.HasFriendlyUrl)
 {
     url = SPUtility.GetFullUrl(SPContext.Current.Site,
          TaxonomyNavigationContext.Current.ResolvedDisplayUrl);
  }

Programmatically Create TopLink Bar in SharePoint site collection:

SPNavigationNodeCollection topnav = oweb.Navigation.TopNavigationBar;
SPNavigationNode node = new SPNavigationNode("Title", "URL");
node = topnav.AddAsLast(node);
node.Update();


Similarly, To create Quicklaunch bar

SPNavigationNodeCollection topnav = oweb.Navigation.QuickLaunch;
SPNavigationNode node = new SPNavigationNode("Title", "URL");
node = topnav.AddAsLast(node);
node.Update();