1,2. Then stop blaming Velanna and alike elves for hating humans. They have a good reason to feel this way
3. Uh, no. Orlais sent templars inside a country without it's permission. Most proofs about Red Crossing are Chantry-based and even if they happened it was one bandit group. If Orlais had been invaded before by elves Chantry would never let us forget that
1) They're still racists. There are lots of reasons for them to resent what happened historically. That doesn't change the fact that Velanna is a racist elven supremacist at the start of the game.
2) The Chantry doesn't let us forget that, because like you said in your own post, their official position is that Red Crossing started the war. And even if that were false, it doesn't change the fact that the Dales (a) sacked Montsimard and (
sacked Val Royeaux. They were the aggressors in the end, and they were well on their way to eradicating the entire country before the Exalted March was called.
When you rape and pillage two cities as an invader, you lose the moral highground (even if you had it to start). The elven response to a small incursion of templars is disproportionate and borderline insane. If Orlais sent templars first, it was a violation of sovereignty but it was a minor one. It certainly doesn't justify a military invasion.