That room in the Caverns is from a different (physical)level I think. I spotted it aswel. But there is no leading way in.
This thing with the vampire. I tried it and yes it shows a female figure an health bar. Both dissapear when you gate and return. But even when you finally have reduced the healthbar to 0, it doesn't give you the exeprience points needed.
So no real bonus here then..
