I've applied for two writing jobs recently, one for a guidebook and another for a blogging gig. In both cases I didn't send the required information, such as a CV, clips, etc., because I had questions about the job first. For the blogging job I found the announcement two weeks after it was posted, so I wanted to make sure it was still open, and for the guidebooks there were two possible books I could have done for them, so I asked which would be the better fit.
In both cases the editors got back to me and gave me courteous and informative replies that helped mold my query into something that would make them more likely to say yes. I haven't heard back from either editor, but I understand these things always take time.
It's OK to send off a friendly, professional email asking for more information, especially if you include enough details about yourself that they can see you are serious and capable. Just remember that there's nothing wrong with querying about querying!