The 4 wire heated sensor is most likely a BOSCH lsu sensor so well up to the job.
Of the white wires 1 is earth 1 is live, doesn't matter which as this only supplies the heater circuit for the sensor, the sensor earth is through the body/exhaust.
I can't definitively help with the metre colours/functions all I can say is in EU black is always signal, but in other countries can be almost any colour, blue being a fave!!
tabetha