1. Yes
2. Unfortunately, some things were left out of the anime that were in the books. Although, to be fair, the earlier revisions of the books were very thin on character development as well. I imagine for the anime writers, it was like trying to squeeze water out of a rock. In that regard they did rather well.
3. Oberon did actually nerf her stats.the greater pity was that they cut out the whole part where Kirito and Leafa were in Nifleheim
As far as Asuna and Kirito dieing, yeah, that was some bullshit. And for moving everybody to a secure location, it's kind of bs but apparently while Kayaba was explaining to everyone in the game that they were all now trapped in said game, his assistant somehow managed to inform police, hospitals etc. that he's has essentially taken their family member hostage and that he will give them a small leeway to get them to a hospital or somesuch. Needless to say not everyone made it to a safe place because they were in some remote location and just slowly died away, or they tried taking the helmet off them, killing them instantly.