So can you get to the extended cut right after loading the final save (just before the Star Child scene), or do you have to play the entire game from the beginning?

I purchased all of the Mass Effect games for Xbox 360 and all of the DLC. I did NOT get the iPhone games, the novels or any of the comic books, and I don't feel like I've missed any "fundamental details" by not getting them. Kahlee Sanders is a major character in the books, but her backstory is summarized well in ME3. The same is true about Aria T'Loak in the comics. But wouldn't it be nice if you can walk up to these characters and ask them questions about their lives before the Reapers showed up? Oh wait, you can!