There seems to be a lot professionals on the board who have insight into work life in France. In your experience, is there much need for bilingual admin support in French cities? Particularly in Lyon or Marseille?

Companies are tightening their belts at the moment, so I wouldn't think they are taking on new "admin support", bilingual or otherwise. Not quite sure what you mean by admin support, but look on the national ANPE website for job offers in Lyon, Marseille or wherever, but expect a lot of competition if there are any that suit you. Sorry to be pessimistic, but that's the situation in France at the moment...

So far, I've only seen ads of this type in Paris.
There is an agency here

http://www.dorothydanahy.com/intro_210205_content.html