Congratulations on your new job--you sound so excited!
Depending on where you're moving from, your definition of vibrant nightlife will vary some. I think that it's improving all the time.
Interracial relationships are relatively common in the Triangle, so I wouldn't worry about the dating scene.
If you can, when you come to rent an apartment, focus on the area downtown, near Glenwood Ave...
(I'm from Durham, and am hoping some Raleighites will come give you more specific tips...)