It is possible hide faces on geometry that you're editing. To do this, select the faces you WANT to work on, then in the panel menu select show-->isolate select-->view selected. This will hide all the faces that were NOT selected allowing to work more comfortably with the faces you need to edit. This is a neat trick when working in those hard to reach areas that are blocked by other faces (for example inside a mouth). To show all faces again, repeat the same steps (note that there is now a check mark next to view selected).