The Tywin scene is meant to replace much of the inner dialogue that Catelyn has during the Vardys vs. Bronn battle where is hinted at the upcoming events near Riverrun. As for the butchering of the stag, that's both a pointer to his part in the death of king Robert, but it also seems to be inspired by the bookversion of Sam's father.
As for the brothel scene, I agree they could have done that without boobs (this was over the top for my taste anyways), but having seen the episode twice now I understand they had to put in Littlefingers past somewhere. His boundless ambition and his jealousy for Ned come together in the final line of this episode very nicely.