1) Her name is likely spelled Eileen. That's how my middle name is spelled, and that's how the Irish band Dexy's Midnight Runners spelled it for Come On Eileen. Which I have had stuck in my head since last night.

It seem to me that they were pronouncing it more like A-leen and not I-leen? Maybe not. (And yes, Come On Eileen would have been a good song choice for this episode!)

I didn't read it as Dean being surprised at the idea of them not living a long life so much as Dean being surprised (and concerned) because it was Sam saying it. Sam is always the one talking about being able to see a light at the end for both of them, and about finding love with someone who understands the lifestyle, and sunshiny sentiments like that. And here's Dean saying something Sam would normally be ecstatic to hear Dean say, and instead Sam is dolefully contradicting him instead. It dovetailed nicely into the graveyard scene after it with Dean checking in with Sam, and the bunker scene before it with Dean being concerned with Sam's post-Cage behavior – Dean investigating Sam's mental health and building a solid case for himself that something was wrong with his brother.

Yeah, okay, that makes a ton of sense.