RSS feed for author and category posts/comments

Hi,
I would like to lunch blog site for more authors (in status “author”). I imagine the structure of site as this:

in the body of

main page – most recent posts (as implemented)
author page – most recent posts from SELECTED AUTHOR (found code in documentation for this)

categories page – most recent posts from SELECTED CATEGORY (as implemented)

post page – selected post and comments (as implemented)

in the sidebar on all pages

list of authors and list of categories and RSS (2.0) links according to the body content (links for most recent posts/comments from all/author/category/post, on post page of course only for comments)

By default, WP (default theme) gives post/comment feeds for ALL posts, and comment feed for selected post, I looking for php code for author and category feeds

Thanks for help in advance