Award tickets are almost always booked (the one exception I know was AF* operated by AY) as prime flights (i.e. marketed by the operating carrier). I have booked a Delta award DTW-NGO through VS, and it had a DL flight number.

You will definitely get free bags, lounge access (for GM+), and priority check-in/boarding. I'm not sure whether you will get a C+ upgrade, because usually that requires the booking code to be changed to SU. I'm not sure if this is a re-validation or what, and whether DL can do it on another carrier's ticket stock.