A WordPress blog can either be structured as a page based website or its conventional post based structure can be retained. That’s why understanding the differences between posts and pages, http://en.support.wordpress.com/post-vs-page/ comprehending the SEO implications of creating a page based structure, and knowing how to use custom menus http://en.support.wordpress.com/menus/
are key to decision making when selecting a theme, and setting up your WordPress.com blog. http://onecoolsitebloggingtips.com/2010/05/12/better-blogging-at-wordpress-com-pages-and-posts/

If you are under the impression you can design your own theme or edit templates or themes then know you cannot do that here at WordPress.com. If that's your intention then you need to purchase web hosting and set up your own WordPress.org install. Here's a comparison for you to read > http://support.wordpress.com/com-vs-org/

On one hand, none of the characteristic "blog" features likes categories, tags, authors, dates, etc. can be removed from a free hosted WordPress.com blog without purchasing an annually renewable custom design upgrade and doing the required CSS editing.
http://en.support.wordpress.com/custom-design/
http://en.support.wordpress.com/custom-design/#frequently-asked-questions
http://en.support.wordpress.com/custom-design/editing-css/

On the other hand, one can hack a WordPress.org theme free of charge. Have you read this comparison? WordPress.com and WordPress.org: The Differences http://en.support.wordpress.com/com-vs-org/

Thank you,
Dave
[email redacted]
Blog url: http://dnierle.wordpress.com/