I would like to reiterate my previous point: Highsmith makes people empathise with sociopaths. She is bad for you! Damn her compelling prose style. I like your character assessments very much, you have Ripley down brilliantly, though you know I disagree very slightly with your stance on Bruno...
But he is much, much more likeable than Ripley, despite his extreme childishness/selfishness. I found Ripley really quite antagonising, I don't think he's actually likeable enough to quite work as a Charming Sociopath (a character genre that surely deserves a post of its own, considering its importance to the subculture...). But it's a while since I read any Ripley.

And I still prefer Carol to both of them.