Yeah, Kreacher got screwed, you're completely right. As for communication - I wish they could've talked everything through! Then maybe they wouldn't have been so doomed, though talking has never been Severus's strong suit. I don't know if Regulus is any better at it.
(And Severus absolutely has the jumper!! (Except there's a slight possibility that in the as-yet-unwritten-Snarry extended edition of this fic that he's given it to Harry.))