Online Journal with WP 1.5

Hello guys,

I decided to use WP 1.5 for one of my projects. This will be an online journal where doctors will write about cosmetic surgery. You can take a look of template here http://www.pcshaman.com/projects/journal/.

I need to start implementing (x)html & css template into WP. So my first question will be what is the best way to create site architecture? Using parent pages or using pages in combination with categories?

I really need you help to understand how WP works so I can finish this projects.

thank you in advance,
Dragan