RE: OAD
Landa didn't want to be put in front of a jury and was getting out early.
We know Germany would lose and that there would be a war crimes tribunal. Landa didn't. We don't get any indication in the film that Germany is losing or that Landa thinks they are and he's worried about his future. Tell me specifically what details in the film back up your statement about Landa.
I can give you one very clear one: in the scene where Hitler decides to attend the premiere of Nation's Pride, he says that the Allies have just recently landed at Normandy. At that point, things weren't looking particularly good for Germany, and any smart German officer who wasn't blindly loyal to Hitler could see that.
As for your questioning of Landa's betrayal, that's even simpler to pinpoint. Think back to the (excellent) first scene where Landa compares Jews to rats, saying that Jews are capable of doing anything to survive and he can think in exactly the way they do. Landa's betrayal is him behaving in exactly the way he described - he's doing what he can to ensure his own survival.
And for one last comment regarding Landa taking offense to Von Hammersmark insulting his intelligence, I think the best piece of evidence is in the "speaking Italian scene." He keeps forcing Raine to repeat his name in his thick Tennessee accent, and makes Donnowitz do the same thing when he fails to mask his Boston accent at first, embarassing and unnerving both of them as punishment for creating such a pitiful facade. But when Pvt. Ulmer pronounces "Dominic Dicoco" in a passable Italian accent, he gives him a nod of approval. When it comes to Von Hammersmark, the stakes get raised quite a bit. First of all, Landa and Von Hammersmark have a history together, so he knows that she should know full well that she won't get anything past him, especially such a ridiculous story as mountain climbing. Add that to the fact that she herself is a renowned actress and should be better than that, and it becomes an even greater offense to Landa.
Landa defines himself by his intellect, as shown by air of superiority he carries around and his constant need to play mind games with people, such as the the previously mentioned "speaking Italian" scene or his stunt with his pipe at the farmer's. He also demands that he be respected, which you see when he is the only German officer who treats Zoller like the private that he is. Ergo, if you don't respect his intellect, you are directly insulting Landa - and as a punishment, all is fair in love and war I guess.
(And as a more roundabout explanation, the film is about propaganda, which is only as effective as it is convincing. Hence why the characters who fail to be convincing, Hilcox and Von Hammersmark, are punished.)