Ava said something to the effect (to EJ) that there was nothing left of Susan's body, as the car exploded and burnt completely. I know I saw a figure running from the car, (which probably was Ava. Susan might have escaped the other side, but who knows. These writers kill people, raise them from the dead, or find a reason 3 years later to have them appear, having been in a hospital, or had amnesia, another life......whatever.
Very few Salemites ever go to church, unless it is to be married, perhaps. Even Eric, the ex-priest, never goes, or mentions it. Caroline was the only one.