I didn't say the Fall of the Dales was part of a deal. The land itself was. I know this.
Indeed. They were offered land. They got land. Deal complete.
Keeping said land requires being tolerable to your neighbors, especially the ones who can destroy you if they don't like youo enough. The Dalish failed at that.
As for the truth of the story, we'll run around each other in circles, I'm afraid. The writers give two versions of the story for the very fact that you and I can fight about it now. 
They're screwing with everyone. Pick your poison.
Well, they really didn't. The Dalish and Chantry versions aren't contradictory.
They also produced World of Thedas, which on meta-level is the official standing position of the setting in terms of facts and events.
But what I don't care to hear is your "solutions" and talk of integration. I'd rather there be conflict. That's what it was created for. Until I'm notified otherwise.
Ok. And?
I mean, people like Velanna doing stupid things for stupid reasons and getting people killed is technically a solution. It's not necessarily a solution to any of the problems cited as motivation, but it does demonstrate resolve and a desire for doing... whatever one thinks you're achieving by doing such a thing. I'm sure she was teaching those Humans a lesson, albeit not one she probably intended.
Personally, I don't hate the elves so I don't advocate continuing a self-destructive culture or direction. I also feel there's conflict enough in simply integration to make for plenty of fodder that would interest me.