It is very possible that in order to get the Mangekyou Sharingan you have to sacrifice either a part of yourself or someone close to you. But from the way Sasuke's Dad explains it, it may not be that dramatic. It may then be possible that the guy who was killed might have been helping Itachi fulfill the requirements in other ways other than dying, in order to gain the Mangekyou.
About the flashbacks, I'm finding them a tad annoying. Yes they provide more information and insight into Sasuke's and Itachi's character which is great, but all I want to do is see the match between Sasuke and Naruto unfurl without interruptions.