There should be an upgrade or some kind of system that makes your money generate whilst offline, but just not as much. Maybe 25% is gained whilst offline?
This game needs to feature to trade cards for other cards, I think that would be a good thing to have, Afterall another mans trash is another mans treasure.
Did you make sure your Kongregate Account is not set to private mode? On top of that, your friends need to add you to their friendlist as well.