For a simple setup you should keep it simple. Forget the cedar. Straight humidifiers that you toss in upright with the sticks sounds good. Make sure they don't leak! A flat one needs a flat space, either underneath the sticks, or on top, but only if all the cigars are the same size, or it won't be flat. Underneath will make the top not flat.
Hygrometers are notoriously inaccurate. Unless you can manage to make them more accurate, and there's a way, forget them. Someone else will explain the way. Keep the cellophane on the cigars!