For the RSS feed you have two options:
1) Use the built-in "Page List" block and turn on the RSS option. It is limited to only show the titles, dates, author, and "description" attribute. If you want the blog to also show some content from each article itself, use the free "Page List Teasers" addon from the marketplace:
http://www.concrete5.org/marketplace/addons/page-list-teasers...

2) Purchase the excellent "RSS Feed Creator" for $15:
http://www.concrete5.org/marketplace/addons/rss-feed-manager/...
...which lets you choose any portion of your site to become an RSS feed (and will show the entire contents of each page in the feed).

To create a sitemap, use the built-in "Autonav" block and set it to show all pages from the home page on down. You may need to style this using CSS, but if you install a concrete5 site and check the "install sample content" box I believe one of the sample pages it includes has a sitemap on it (maybe the search page?)

Good luck!

-Jordan

To add to Jordan's advice... if you're looking to create a Sitemap.xml file for search engine submitting... run the system job under the system & maintenance tab and it will be created automatically.