Speaking of the Dark Urge - I am yet to find time and a damn to give to go through the game a second time, but from what I've seen, there's also barely any interconnection between the "you are tadpoled" plot and the "you are a Bhaalspawn or something to that extent, somehow" plot. Is that truly so?
No, the complete opposite is true. I can't tell you why without spoiling the entire plot of the Durge, but rest assured that that is not a problem the plot has.