Personality-wise, the casting definitely fit and she was a great choice. I thought it was kind of cool to get a pseudo-look at what Lisa was like/might have been like had she survived. The only thing that made it "not compute" at all to me was it was just very surprising to me to see her there, given that even though they probably could, Torchwood and Supernatural aren't two fandoms I've seen overlap a lot.

Interesting point on the husband thing; I hadn't even thought of that. Honestly, from my perspective, I don't think they're an issue at all. The only thing that comes to mind as a reason the writers might have gone with making her husband black is to provide a contrast (with both her and her husband) to the only other black hunter we've seen in the show, Gordon Walker. Since Gordon's been established as a pretty loose canon, I think they may have wanted to offset that by showing there are other non-white hunters in the country who are a little more on the ball.