I was responding to a different quote in every case. Sorry my work flow sucks. My bad!
There's also an "insert quote" function, or you could open a new tab when you quote someone so you can copypasta all the text into one message. Could you please edit it into one post? I'm sorry to sound rude, but it looks so annoying to see four posts from the same person in a row like that. I mean, fine if nobody replies and sometime later you bump it with a new message, but in a situation like this is just...no. It's like somebody says something in a conversation, turns around to leave, and then turns around again and yells "And another thing!" Multiple times, too.
Back on topic, I don't think it's right to be weighing lives cost versus lives saved like it's some kind of zero-sum game. Without going so far as to say something trite about it being the thought that counts, what's important about Vader's redemption is that he finally managed to turn against the Emperor and do some good. I don't know if anyone would say that "excuses" the terrible things he did, but it was enough to show Luke the good man that his father had once been wasn't wholly gone.
The prequels, of course, managed to ruin this contrast by portraying Anakin Skywalker not as the brilliant Jedi, loyal friend, and all-around awesome guy that the characters in the original trilogy described him as, but as a spoiled, selfish, whiny asshole who was only ever a mediocre Jedi. But bullshit from the prequels is best left ignored in a case like this.