You have to use the object tool rather than the model tool to animate scale, or else you can use the coordinate panel in the attributes manager. If it’s a primitive you can animate the primitive properties.
You could use a step effector controlling Y position to bring the cards to a fixed height. I’d set the falloff to linear and then nest it under the animated random effector so it moves in tandem. Then adjust the transform/Y amount and falloff to taste.