Europe is different of course. I am a US Citizen too, and do file my US taxes but only pay to France. If you want more help, see those trying to help us Americans Abroad, I am a member for many years and do participate actively in the community here, see
www.aaro.org

And we get together in Paris, have done meeting in Brussels and other French cities, maybe they need to do one in Madrid ::)
http://www.meetup.com/american-197/

Hope it helps