I have a situation where I need to mess with a breadcrumb on a page and insert some items in the middle. In my instance drupal_set_breadcrumb() can't be used, so I need to implement a hook_menu_breadcrumb_alter(). I am a little confused about proper usage with this, though, and am not terribly familiar with the guts of how the menu module works.

Is there a proper method for building elements that go into the $active_trail array? It is easy enough to figure this out from what is there, but I would like to do "the right thing".

Is there a proper method (or best practice) for testing whether $item is a node and to load it. Again, I can dpm($item), poke around, and get what I need.

I have what I need working, but it is messy and would like to fix it for the long term.