With regard to point 3, there are some quirks of the intelligence system to keep in mind. IIRC the range of hostile sensors is estimated purely from their GPS (EM signature), so the range increase from EM sensitivity techs is completely ignored. This means the true sensor range of their sensors may be much greater than what Aurora might draw. Res-1 sensors typically have very low GPS, making them virtually undetectable until basically point-blank range. The NPR ships you encountered likely did have res-1 sensors, but you just lacked the sensor strength to detect their low emissions.