When I go to the homestead, my dialogue options indicate that I've met a strange woman. No such woman exists. The only room I've got unlocked is the great hall and she's not in there. Is this a bug?
She will wander off after you initially meet her. I don't think she'll do so until you've actually had a dialogue, but if the table is now empty then the script somehow fired without that. If so, post again and someone can probably spoil you what the dialogue would have been.
No, not really. She calls your characters the guardians, says you've become as weak as you once were strong, and leaves. Walking away, she says 'he won't believe me' and 'I knew they would come / could they still save me?'.