Without knowing anything about your current website (intranet or outside the firewall, Java, PHP, etc..), I can tell you that we do add recent blog posts to our various communities (this one and igniterealtime.org) using a combination of RSS and webservices (SOAP). You should be able to get the most recent blog posts feed using this URL:
By default the feed should contain the entire entry body for all the posts in the feed. The add a comment feature would be harder.
Comments are only associated with documents and blog posts: the analogous object type for discussions is a message (which is a reply to a thread).