I think it is more of a consequentialist application of Kantian ethics. Kant was all about the motives, and said disrespecting another's human dignity should be avoided because our rationality tells us to respect each other. But, that leaves some strange things open, which may however play into your second point. If someone dies because you lie, Kant says you did the right thing (as long as it was motivated by duty to rationality). I think most people would disagree. But of course, that situation is likely to be rather rare.Generally, any action which benefits an individual at the expense of others is probably going to be wrong, especially if there's something underhanded in it. This definitely isn't a bulletproof heuristic, but I think it works pretty well. I guess this would qualify as Kantian?
You are absolutely right, I thought one thing and wrote the other. That's always what's troubled me too. Why not both? I can see that if someone has good intentions, but it turns out slightly differently than they expected, they can't really be at fault. But sometimes people just mess up so badly, they have to be held accountable., but wouldn't Kant say that if someone died because you told the truth, you did the right thing?
I think both the "means" and the "ends" are important,