Below is a twitter thread, written by Jorge A. Caballero, MD, that answers the above two questions. It is definitely worth reading.
Source: Mosquitoes now spreading Zika virus in US, officials warn – National | Globalnews.ca
According to US health officials, mosquitoes have begun spreading the Zika virus in the U.S. Thus far, four individuals have been infected in the Miami area. Although no mosquitoes have actually been found in Florida that carry the virus, other means of transmitting the virus have been ruled out in these four cases. Therefore, as Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention states, “Zika is now here.” Click here to read more about Zika virus in the U.S.