i'm going to have to side with 'is' in the 'is or are' question. i don't think most people would say, 'which one are worse, tornadoes or hurricanes?' since there are only two things for the 'which' to operate on, it seems to be a case of one or the other--that is to say, it's asking which one of the two is worse than the other. so even though there is a plural there, it's a choice between one of two things. for 'are' to work, i think the sentence would have to be something like, 'hurricanes and tornadoes, which are two of the deadliest natural disasters, are not particularly fun.' that said, i have a history of being completely wrong most of the time.
blue: my best wishes to you and your family.