If this were to come to fruition, it's important to note that re-posts of the same link would be permitted. I only mention this because it always seems to be the next question. -justifiably. It would be unfair to not let someone comment on a link to an article by ignoring them when it is of interest to them. They could then repost this article themselves and discuss it with people in another thread. While I don't see this happening much now, it could be more prevalent in the future.
Not currently, no. If you post a link someone else already has it automatically redirects to the original post.
Personally, as someone who reads more than I'll ever likely post, I kinda prefer that in a way. One of my problems with reddit has actually been when big news breaks and you want to get a bunch of different perspectives on it, you need to hunt down posts about the news across several different sub-reddits. This also nips reposts (and the incessant complaints re: reposts) in the bud as well as promoting discovery. Kind of a neat bug if you ask me.