Actually you are not suppose to charge the insurance company one rate, then charge the patient another. This is a very common question. We have looked into it at great depth. Being non par makes it a little different, since they cannot remove you from their panel, but if you are a participating provider and you charge the patient less, the insurance will remove you from their panel if they find out. In any case, it is highly frowned upon by insurance carriers. I am not sure of the legality end. I wouldn't recommend it unless you can find a creative way to show a reason for billing the lower amount to the patient.
As far as when the benefits are exhausted, it is kind of the same rule. However, this one is a little easier to get around. If the patient is a cash patient or if their insurance will not cover the services, you can have a cash rate that is on a sliding scale, and make the lowest fee at such a level that all patients fall into it.
Hope that helps
Michele