Drupal 7 Views, paths, node associations via taxonomy
Sorry for a general answer, but it may get you in the right direction anyway.

What you seem to need is to establish relationships in views. By adding a relationship, you just add an object you would like to refer to. Once you add a relationship (on the right hand side, in Advanced panel), additional fields appear in the Add Field and Filter dialogs. Note the dropdown list that appears in field-related dialogs that contains relevant relationships that you have defined. You may also have a cascaded relationship (a relationship that uses another relationship).

All that translates later into the WHERE clause of the final query which filters what you want to show/hide.

To use the elements of the path, you want to use Contextual filter where you specify which part of the URL means what. 

One thing to remember is that, even though you have clean URLs turned on, there is an "unclean" URL query behind the scenes which contains stuff like term IDs or node IDs. Perhaps it'd be useful for you to turn the clean URLs off for a moment, and play for a while just to see what kind of URLs will be used by views contextual filter. Or put &lt;?php print $_GET['q'] ?&gt; somewhere in the page.tpl.php for testing convenience.