Regarding the monster with Ygor's brain: My take is that with each 'death' and resuscitation the Ygor personality is increasingly submerged until the monster's brain has little, if any self-awareness of the Ygor identity. So by the time of the House films the monster is back to being a hulking brute with a brain of a criminal, but with no sense of the of the brain's previous existence as Ygor (other than vague trace memories), and the violent inclinations/instincts of the criminal brain. So in effect he wouldn't be all that different from the state he was in in the Karloff films other than a somewhat reduced mental capacity.