Gasket elements only deliver a nonlinear force-displacement response in a single direction. I can only be done with a single element though the thickness. There is no benefit and only harm to have a node between the two faces.

The gasket element is very different from what a solid element does for an elastic material, which is to respond to forces and moments in all six DOF and have to compute stress and strain. To do this with some accuracy, it is better to have two elements through the thickness.

Gasket material has no damping properties. It is primarily used in Static Structural models. 

To evaluate the seal quality, plot the gasket pressure and closure distribution over the entire surface area. Check that a minimum threshold of gasket pressure is present over the entire joint area that encircles the opening where you what to hold some pressure load.