Fever shows up after 12 to 14 days of incubation. After another 2 to 3 days, the first rash appears. The virus becomes transmissible as soon as the first rash is visible. It is VERY transmissible via droplets from sneezing and/or coughing. The infected individual will be feeling like crap and not much interested in running around. Using infected people to pass the virus through airports would require careful timing to deploy the person when they are contagious, but not evidently ill to a casual observer.
It is possible to culture the virus and infect people with a simple aerosol. It takes very few particles of virus to launch a viable infection.