HotDog,
donīt know how it is in OZ, but itīs not uncommon here not to have primary radar data available for sectors working the upper airspace. In fact, most of the new antennas donīt have this capability anymore and are secondary only unless they are ASRs...
Regarding TCAS, Iīm sorry for my "stupid" question, but our training doesnīt give us that many details...I think we are not supposed to know....