Hi Eric,

The Style dropdown in FCKeditor is populated from some predefined formats, you can define your own and its possible to leave out the ones I have defined.

See http://www.mojoportal.com/creating-content-style-templates.aspx

I have no automatic magical way to discern from the css what choices to offer users. You can put whatever you like in the css and some of it may be useful for content editors but much of it is not, so you can define which css classes are available in the editor by defining style templates that can wrap content in a specific element and apply a css class. Its up to you to make sure the defined classes exist in the css and to determine which ones are useful for the editor.

Hope it helps,

Joe