See here for details of all 3 plans http://store.wordpress.com/bundles/
Note that none of the plans allow you to run advertising or to upload your own themes or plugins. WordPress.com blogs cannot be equipped for eCommerce transactions. If you need a site that requires a custom theme or plugins — e.g., if you want to be able to sell things directly from your site, or if you want to install discussion forums — a self-hosted WordPress site might be right for you.
WordPress.com and WordPress.org are completely separate.
Do they promote premium blogs, include more ads to boost revenue, etc?
There are no statements made to that effect, however, I observe that the blogs that are featured in posts as examples in both Staff blogs are blogs that do have upgrades and not particularly the business bundle upgrade.
Staff blog 1: http://en.blog.wordpress.com/
Staff blog 2: http://dailypost.wordpress.com/