I was wondering about all those things, too. I know that Vicki was very interested in the family history, though, and especially in Josette, so she might have learned some of those things, and it wasn't shown on the series. I did wonder whether Barnabas had told her some of these details.
Yes, she should have immediately realized that the ring that Countess Dupres described was Barnabas'.
I thought Victoria was actually coming across as a bit more mysterious -- even witchlike -- in that scene.
What I've wondered (and others have no doubt mentioned elsewhere) is how she does NOT seem to be aware of any of these deaths until suddenly right before they're supposed to happen. You'd think that once she realized that she had been catapulted into the past that she would have studied that Collins Family History line by line!
On the other hand, maybe she DOES know which characters (I mean family members) are destined to die, but for various reasons has not said so. But that's not too in keeping with Victoria, who tends to blurt things out without too much thought!