Does the VRE equipment have cab signals? If so, where do they use them, on the CSX side or the NS side or just Amtrak in WAS.
Yes, VRE engines and cab cars are cab-signalled as well as being ATC and LSL-equipped. The ATC equipment is for the ex-RF&P territory (south to Richmond) while the LSL is for the limited Amtrak trackage that they utilize. The northern part of the ex-RF&P does have exemptions for non-ATC & cab-signalled equipment (mostly for NS moves) from AF Tower north.
On the NS (ex-Southern) side itself, there are no cab signals (and neither the nearby ex-B&O lines).