One question though...How do you create a specific Media Sub Type...For example, instead of Movies I'd like to sub divide into War Movies, Westerns etc.
I asked this exact same question when I started with MC!
It turns out that Media SubType is very specific for MC. It is only used for predefined MC things. Like Home Movies, TV Shows, and Movies.
To subdivide your collection, use a different tag. I can't check right now, but I think one of the standard tags for MC Movies is [Genre]. If not, I know [Keywords] has many different values assigned for various movies. Take a look at the existing tags and you may find that you already have something set to the value you want by the automatic metadata scrape that pulled in the movie title, description, actors, etc.
You can then set up your views to use the tag or tags that you want to show you only what you like. I highly recommend playing around with PANES views. You can add various panes to the top of a view and then drill down by selecting various values.
Best of luck,
Brian.