I'm sure Euronymus would love you to have thought he ate Deads brains, but whether he actually did or not is up in the air. It is however pretty much agreed on that he probably drove Dead to kill himself. It's worth pointing out for balance that Euronymus had threatended to kill Varg (apparently Euronymus used to send people death threats for shits and giggles (this being Mayhem), however, as we know, Varg is not one to piss about). Varg also swears blind that Euronymus went for a knife before he stabbed him, and it would be worth listening to him because sure as hell no one in court did (though it would also be good to note that Varg isn't technically imprisoned for murder, but rather voluntary manslaughter, also that he was stung for at least two extra church burnings he almost certainly couldn't have actually committed). He's actually as much imprisoned for arson, theft and the illegal possession of high explosives as the manslaughter. Also, as Kadlin points out, Varg isn't actually a neo-nazi. He was a neo-nazi for a few years after he was first imprisoned, but he no longer maintains any contacts with White Aryan Resistance or even the All-Germanic Heathen Front (which he founded, and is anyway not actually per-se a racist organisation). Indeed, there's a rather charming bit on the Burzum website where Varg says he's had to cancel an appeal for people to send him some interesting political/philosophical books because the senders politics were 'too radical'.
Not to say Varg isn't fucked up. Some of his ideas are batshit crazy: he's completely in to Atlantis and Thule and all sorts of similiar insanity.