Post Category Child/Grandchild Displayed Differently

Hi all,

1)

I’m making a news site and I want to organize it in a way that:
a) Each day’s posts of a particular section (e.g. Politics, Finance, etc.) are grouped together.
b) The grouped together daily posts display one way, whereas the archive of monthly posts display a different way.

The way that I have it so far is:

Parent (Category) -> Child (Category) -> Grandchild (Category) -> Great Grandchild (Category) -> Post

e.g.
Finance -> 2012 -> September -> 9 -> Euro Falls to an All New Low
Finance -> 2012 -> September -> 9 -> Housing Boom Leads to New Opportunities
Finance -> 2012 -> September -> 9 -> Gold Prices Skyrocket

Politics -> 2012 -> September -> 9 -> Obama Resigns
Politics -> 2012 -> September -> 9 -> Antarctica Declares Independence
Politics -> 2012 -> September -> 9 -> World Peace Treaty Established

I want to make it so that on http://www.domain.com only today’s politics posts will be displayed, and moreover that ALL of today’s politics posts will be displayed (regardless of how many). However, I only want to display the headline of each post along with that post’s respective picture in a grid-like format (users can then click on any of the headlines to be taken to that post’s page).

The post’s link structure, in all cases, will simply be http://www.domain.com/post-name.

The part I’m finding tricky is how can I make it so that this Great Grandchild category displays in this fashion (grid-like format showing only post headline and thumbnail), but make the Child and Grandchild categories display differently (mere lists)?

Or should I be doing this a different way instead of using post categories, or some other way?

Someone suggested to me that instead of making date categories as I have above, to use the existing publish dates already associated with each post. Is that a better way, and if so how about if I want to see the posts for the day of August 24, for example? How would I let the user query that with the lack of its own category? Or would I simply make one post per day (e.g. 2012-09-09) which includes in that post the headlines and thumbnails of all posts posted on that date?

2)

I also don’t know which of the following two category structures are better:

Finance -> 2012 -> September -> 9 -> Post
Politics -> 2012 -> September -> 9 -> Post

or

2012 -> September -> 9 -> Finance -> Post
2012 -> September -> 9 -> Politics -> Post

Thanks!