Rolling Stone and Resignation

Regarding General Stanley McChrystal's resignation, I have a few questions:

1. Why would someone of his responsible level make the comments reported in the article to a reporter?
2. What really happened? Did people investigate and verify the information to find out if it was accurate and true?
3. How does a reporter justify reporting information that will end someone's career? And then feel OK about that? What motivates that level of reporting, or was this a whistle-blowing report of some sort?

I am sad to see a career end this way and curious to know the whole story. Kind of military verbal suicide, so there must be more to this story.