I've just configured Faye for our application, you are doing
bayeux.attach(app);
app.listen(port);
did not work for me, what worked is this
bayeux.attach(app.listen(port, function() {}));
I also think that you should use the whole url when you are creating Faye, not just the final part, like so:
var client = new Faye.Client('http://my.url.com/faye', { timeout: 20 });