Listing users with certain roles…

Hey,
I am looking to make my blog one that once you’re on the main page it lists the users (that have posting capibilities – Admins, Editors, and Authors), and when you click on the user it shows all the posts by just them. I’d also like to make a link show all posts by all authors. Is there a way to do this “easily” if so, could someone please let me know? By the way my site address is http://www.notablogproject.com/.
Thanks in advance,
Gordie