1) How did they guarantee that the virgin was the last to survive? They mentioned that the virgin had to be the last one alive for the ritual to work, but it seemed like they were relying on pure luck for it to end up that way.
2) Was the ritual different at the different locations? The Japanese ritual had a bunch of young school children, so I'm pretty sure the Jock/Slut/Virgin/Nerd/Fool setup would not be part of theirs (at least I hope not).
1) Could be luck. Or could be they're controlled somehow on who to target and when.
2) Yes. The rituals are different based on different cultures. Just like horror movies.
You are sin.
1) well the monsters were attacking them in the order they wanted them to die. The zombie in the van could gave killed the virgin before the scholar
2) Remember Sigourney Weaver's character saying 'we work with what we have' towards the end of the film. The virgin wasn't really a virgin but represented one more than the other 4. For the Japanese kids it would just be who represents these different personages the most.