Can Cass predict what your character is thinking/planning/doing? Yes for fighting. For other thoughts I would say tentatively yes, although it may be more difficult since Narvin is an alien and his species' body language may not be quite like a human's. And when he's *really* trying to hide something he (like other Time Lords) can consciously control even things like pulse. But unless he's Up To Something, he probably won't be exercising that degree of control. And if Cass spends time with Gallifreyans, she could probably learn the quirks of their body language.
If yes, what limitations do you have on this? As above (in my tl;dr)
Is there anything you'd rather she not be able to predict? Same.
Anything else?