Sage is a lightweight RSS and Atom feed aggregator extension for Mozilla Firefox. It's got a lot of what you need and not much of what you don't.
* Reads RSS (2.0, 1.0, 0.9x) and Atom feeds
* Feed Discovery
* Integrates with Firefox's bookmark system
* Imports and exports OPML feed lists
* Newspaper feed rendering customizable via style sheets
* Support for the following locales: Argentine Spanish, Catalan, Chinese, Czech, Danish, Dutch, Finnish, French, German, Greek, Hungarian, Italian, Japanese, Korean, Polish, Portuguese, Russian, Serbian, Slovenian, Spanish, and Swedish
These details are provided for information only. No information here is legal advice and should not be used as such.