Sage is a lightweight RSS and Atom feed reader extension for Mozilla Firefox. It's got a lot of what you need and not much of what you don't.
Screenshots
What does Sage do?
- Reads RSS (2.0, 1.0, 0.9x) and Atom feeds
- Newspaper feed rendering customizable via style sheets
- Feed Discovery
- Integrates with Firefox's bookmark storage and Live Bookmarks
- Imports and exports OPML feed lists
- Technorati and RSS search engine integration
- Support for a number of locales: Argentine Spanish, Catalan, Chinese, Czech, Danish, Dutch, Finnish, French, German, Greek, Hungarian, Italian, Japanese, Korean, Polish, Portuguese, Russian, Serbian, Slovenian, Spanish, and Swedish
- Simple, one step install / uninstall