RSS Feed for each Category

Built in. ??

Have a look at WordPress_Feeds for more info.

Also, if your theme is using wp_list_cats to list the categories (typically in the sidebar.php), you can add feed=RSS to the arguments to get feed links next to each category.

Hope that helps.

<ul>
<?php wp_list_categories("sorderby=name&show_count=1&feed=RSS&title_li&feed_image=IMAGEADDRESS/rss.png"); ?>
</ul>

take a read of this article How to display RSS feeds on each category
It tells you step by step what to do as well a how to add an rss image to each category.