(Wow this is a lot longer than I expected it to be, but, whatever)
First off, I want to say that I don't necessarily agree with that analysis, but it's pretty interesting (to myself at least).
1. I beg to differ. Considering the subject matter of the film, I think the natural tendancy is to view Pulp Fiction as iconoclastic (versus, say, reflective of dominant cultural values). The briefcase concept can be seen as religious if you believe the idea that it's Marcellus' soul. The combination for the lock on the briefcase is 666, which is commonly referred to as the devil's number. According to the bible (and I'm not, in the least, claiming to be any expert on the bible - I'm not even christian), as friends have told me, the devil takes the human soul through the back of the neck (hence the band-aid on the back of Marcellus' neck). Also, the human soul is described as "more beautiful than all the treasures in the world" in the bible - Tim Roth describes the contents of the briefcase as "beautiful" when he sees it. And God protected Vince and Jules from the "hand cannon" used by the kid that came out of the bathroom because they were saving one of God's souls. There are also some other religious interpretations, for example Butch and Fabian are symbolic of Adam and Eve, Vince is Judas, etc., but like I said, I'm no expert on the bible, so I don't think I can fully comment on them.
(It should be noted that in an interview, Tarantino himself said that he purposely left the contents of the briefcase undefined, so I guess it will never be known what was actually in it.)
2. The significance of cultural relativity comes down to a clash of widely held, majoritarian views (i.e. typical attitudes) vs. the cultural minority. Travolta talks about the different weight systems, different name for Quarter Pounder, etc. to show Jackson that there is no absolute truth or absolute way of doing things. In other words, different cultures do things differently, and the way one culture does something is not wrong because another culture does it differently. Religion, however, is the opposite of cultural relativity, because it represents an absolute truth (e.g. believe Christ is your savior or else go to hell). Religion, in effect, does not accept the different ways that cultures view things. Travolta accepts cultural relativity, rejects religion, and eventually dies. On the other hand, Jackson accepts religion and lives. This is the irony - Pulp Fiction promotes acceptance of the opposite of what most people would associate the movie with, i.e. accept the norm; accept what society tells you to accept.
3. According to the author, Big Kahuna is a Hawaiian phrase for "high priest." Before Jackson took a bite out of the Big Kahuna burger, he accepted the culture relativity exposed by Travolta (during their conversation in the car about the different weight systems, etc.) After he took a bite of the burger and almost gets killed, Jackson accepts religion and lives throughout the movie. On the other hand, Travolta refuses to take a bite out of the burger, and thus refuses to accept religion, and ends up getting killed by Butch later on.
4. To be honest, I don't really know if the price of relativism really is death. Vince wasn't doomed at this point, however. After "God came down and stopped the bullets" from hitting him and Jules, he was given a chance to accept religion, but didn't. (I guess the timing is a bit off, but you could look at taking a bite out of the burger as a precursor to acceptance or not.) Remember Jules kept wanting to chill out and talk about the "divine intervention", but Vince didn't care about talking about it at all. Vince had the chance to accept the religion later on as well, when Jules called what happened a "miracle", "an act of God", but Vince blew it off as a "freak occurrence" in the coffee shop. This, in effect, sealed Vince's death.
5. Actually, the person who wrote this is a law professor. The book this comes from is actually an excellent book on racism (best book on racism I've ever read). The book is Negrophobia and the author is Jody David Armour.
There's A LOT more than can be said about the details that are woven into this movie, e.g. the gun Butch uses to kill Vince is actually Marcellus' gun; Butch is the one that keyed Vince's car, so Butch is the one Vince is referring to when he talks about the "dickless piece of shit that keyed his car"; at the pawn shop, there is a sign for Killian's Red Beer, but the only letters that are lit up are the ones that spell out "Kill Ed", well, later when Butch gets on the motorcycle, he looks at the key chain, which is in the shape of a big letter "Z" - this adds up to "Kill Zed," which is exactly what he did, etc.
Prior to watching this movie, I had never seen a film that had interwoven stories that came together as beautifully and seamlessly as these stories did. What makes the movie great in my eyes is that I can watch it over and over again and appreciate new things about it almost every time. I can't say that about many movies.