The new strain of swine flu has killed 103 people in Mexico and spread across North America and possibly as far afield as Spain and New Zealand. And experts say they are not sure of how powerful the strain is, how it may be transmitted, or how severe the symptoms may be. But there are some things they know about swine flu. Here, a health reporter has compiled all of the available information about swine flu into one list, including its symptoms, how it's spread, and how long an incubation...