I think, people can read too much into the virtual characters and daydreams. They can be something or nothing. Ron's kept it ambiguous for exactly those reasons. Orgiginally, the virtual characters developed because they added a neat dynamic and the near death experience of Apollo and Adama's wistful daydream may be no more than that or may point towards an overal narrative goal. That said, Mrs. Bill is an interesting speculation and quite fun to consider!

Your suggestion for Roslin's collapse is pretty credible along with her taking kamala. Also, you comments about children throw up Ron being a bit ambiguous about whether Hera is the first hybrid child. I'm less inclined to thing Kara is the final cyclon as that would tip things too far towards BSG being The Starbuck Show.
If that's all it's about they can pack their bags and never finish it for all I care. If I can run with your idea about Kara's missing father one speculation could be that Romo Lampkin is in the frame for that. I mean, if someone got a girl pregnant then walked I wouldn't be surprised if her mother was in a perma-piss.