Yeah Stroud is so easy to leave in the fade haha... poor guy, he never had a chance...
He does for my beau and I. We always spare him and never think twice about it. 
(My beau because he's a casual DA player who just found Stroud more likeable, myself because I never liked DA2 or Hawke.)
Yeah, this. Particularly the point about role playing. For some players, it only matters what your character knows, and there are lots of ways to play the lyrium choice depending on who your IQ is. So I just don't think it's as black and white as whether the IQ cares about Cullen's well being more or less than the well being of the Inquisition.
I've actually not paid much attention to whether the "we'll find a solution" leads to a happy outcome so that's good to know. The wiki only lists it for continuing the Inquisition and without romance. I assume it has a good outcome either way? Someone should add that in.
Yeah, that's part of what I like about DA games. BioWare leaves things blank enough (unless you're Hawke) that you can roleplay why your character says or does a number of things they do, but I also like how characters might interpret it differently.
For example, with hindsight on my side I realized that Cullen wants to go off lyrium to better himself, and the only reason he falters is because he's afraid he'll be of less use to the Inquisition. Regardless of your internal reasons, if you tell him to stay the course he interprets it as you supporting his effort to better himself, and he appreciates it. Even if your internal reasons are very noble or altruistic (save him from dying, hope to help him kick it later, etc), when you tell him to go back on lyrium, he interprets it as you saying, "You're right, you should put the good of the Inquisition above your well-being," and he kind of resents it. Even if he agrees with you, he's skill kind of bitter and kind of regrets it. And if you're in a romance, well--again, regardless of internal reasoning, he doesn't want to be with a gal who says he should put the good of the many before his own well-being.
In a way I like it because what we mean when we say something is now how it comes out. But on the other hand, I kind of like how this game encourages people to be mindful of how our words sound to companions. For example, the aforementioned Cullen situation, and how he might feel that, "Okay, if I'm supposed to put my personal feelings aside for the good of the Inquisiton, then we shouldn't be together either since that's a distraction from helping the Inquisition." Or the Iron Bull: by telling him to sacrifice the Chargers for the good of retaining his ties to the Qun, from his perspective you're basically telling him that his individual feelings and relationships outside the Qun don't matter and that he should put the loyalty of the Qun above all else. Then people get surprised when it applies to them and their relationship. =/
I don't know, just my take on it. I know it's not black-and-white, but I do find it kind of fascinating how our characters might mean one thing but the characters could realistically hear it differently.