Unfortunately, there is not a way to make the News tab the default home page for a Confluence space. If you want to configure a space to be a dedicated blog, you can simply use the {blog-posts} tag on your home page to show all blog entries. The home page for this space also uses the {popular-labels} tag to show the list of labels and their popularity which you see in the right hand column. Here's the full wiki markup for the labels tag. The heatmap style shows popularity using font size, the spaceKey is the shortname of your Confluence space, and the count is how many labels you want to show.
{popular-labels:style=heatmap|spaceKey=blog|count=10}