The answer to your 1st question is yes. Its that simple, yoururl.com/feed
As to the Widgets, it is just as simple. Simply type the URL for whatever RSS feed you want the widget to show in the http field of the "configure" panel of the RSS Widget.
For example if you want the RSS1 Widget to show the RSS feed for the Business Headlines of the NY Times you would type the following:
If you want the RRS2 Widget to show the RSS feed for the CNN topstories you would type the following:
And so on...Hope this helps.