FFF,
RAS is the service I was thinking of, as an aircraft receiving this service would have to be separated from any other known traffic, even if this other traffic was receiving a FIS or RIS, as they would all be IFR.
As to your other point, yes, an airfield in class g is required to separate IFR departures until such a point as this traffic has left the ATZ, and declares that they no longer require a service from that unit.