The Vince McMahon death storyline
2) From what I've read online, if the Benoit tragedy hadn't happened, that night's Raw would have been Vince's funeral (the superstars were all told to wear black suits, Ted DiBiase was brought in to give the eulogy, ...) and the show would have ended with Linda McMahon being taken into police custody as a suspect. From there, who knows? Hopefully, it would have had a better ending than the "Who ran over Steve Austin?" angle (Rikishi?!)
I remember reading something on tvtropes.org (consider the source) that this whole thing came about because USA Network wanted WWE to do a murder mystery storyline. They went with Vince as the victim because he wanted to retire the Mr. McMahon character. How much truth there is to this, I don't know.
3) I think after how poorly received the angle was (I recall the IWC hated it a lot and thought it was tasteless), they won't try to do anything like it again.