What's the best way to structure original vs aggregated content

[ScottDavis]

We're working on a news site that has a mix of news wires such as Reuters and original opinion articles.  Currently the site is setup with /world /sports etc categories with the news wire content.  Now we want to add the original opinion content.

Would it be better to start a new top /Opinion category and then have sub-categories for each Opinion/world, Opinion/sports subject?  Or would it be better to simply add an opinion sub-category under the existing news categories, ie /world/opinion?

I know Google requests that original content be in a separate directory to be considered for inclusion in Google news.  Which would be better for that?

Regarding link building, if the opinion sub-categories were under the top news categories, would the link juice be passed more directly than if we had a separate Opinion top category?