The PowerPress Basic Settings apply when no other setting has been set for a specific category. More important, if you do not add "Category Podcasting" to the specific category, the defaults you enter in PowerPress > Settings are used. If you didn't have PowerPress do this, then you wouldn't have anything podcast related in these category feeds.
On the opposite token, you definitely want to spend the couple minutes and add "Category Podcasting" to your category feeds you submit to places like iTunes. Two very important aspects doing this with PowerPress:
- The Title of the Category feed can be completely customized with PowerPress. If you don't use PowerPress, the Category will be in the format of "Blog Title » Category Name", which isn't necessarily desirable.
- The iTunes cover image, as well as other iTunes attributes, can be completely different than your main podcast feed, giving you the power to brand your category completely differently.
I would go ahead and edit the category feeds (Add Category Podcasting to both) for both your old show, and your new show, just so you are managing both feeds in the same way in PowerPress.
As far as Statistics are concerned, if you add a redirect at the category level, it will only be applied to the category feed. Remember, your audience can stumble upon your blog posts on your blog whether or not they are in a particular category, for this reason the global redirect is used since we have no idea which category, if any, a web visitor intended to view the podcast episode/post in.