Because of the problems with the "Infected Block" theory, especially the time of death aspect, I took some time analyzing the possibilities and came up with what I think it a better version. Skat, instead of Block, is now my original carrier. Take a look at the following flow chart and see if that makes a bit more sense:Skat- infects Lisa with a kiss, who- infects Plogg with a kiss, who- infects Jons by grabbing his arm in the scene where Skat "dies", then dies. Jons then- infects MG with a snuggle in the scene where they watch Raval die, and infects the witch when he gives her water. The witch then- infects Block when he gives her some drugs to dull the pain of burning alive, who then- infects Kurin when she gives him a caressSo this way Joff, Mia and Michael are safe, Skat's death is explained, and the fact that he is the first to die is also explained as he's been carrying the plague the longest. The others all catch the plague within half a day of each other and so it makes sense that they die at the same time in the end.This theory still has a few unexplained facts (why Raval dies, and why Death comes for Block first) but I think that the timing and the lack of connection between the plague and the chosen family is worth it. Ravel could have easily caught the plague when he robbed the dead, as it's shown that he does that for income. Death could also have come for Block for an reason related to his time fighting in the crusades as well. I like this theory also because it means that Block doesn't unwittingly do more hamr than good by postponing his death at the start. In this postulation Block only actually infects one person, his wife.
The last question would be how Skat originally catches the plague, and it would have had to be something that only he did, as he was travelling with Joff, Mia and Michael and they were unaffected. I was wracking my brain for hours today thinking of what it could be and then when it hit it was obvious. In the scene where the travelling players are first introduced Skat emerges from the wagon wearing a stylized mask of a skull, meant to represent...Death. So Skat, who actually "becomes" Death and reads a line from a play ("Your life, oh fool, hangs by a thread. Short is your day!") symbolically and literally brings death in the form of the plague into the movie. The Death mask gets hung on a branch off of the wagon and rests there until the end of the movie, casting a shadow over the party as they travel together. Bing!