I was told to speak to Fura Bloodmouth, and after looking trough every corner of the castle, I can't find her and the marker just points me to the middle of the dining area. Any help?

She is normally in the training room by the dummies swinging her sword (where the anvil is located). I had her not show up once, left the castle and came back later and she was there. You can also check the coffins. She maybe sleeping in one during the day hours.

In my game she sleeps in a coffin in an annexe down next to the Smithing stuff. If you get no proper quest marker for her she is probably bugged, and other than trying to load the cell again or checking if she's in an older save, you could use a moveto console command if you're on PC.