I'm not sure about the 2012-2015 models. When I had my 2010, traffic is received via the XM traffic package. I think the 2012-2015 models get weather and traffic via HD radio signal.
Not any more. If you have the base Four's Display Audio, it's via Entune services. If you have the Deluxe Solar Roof package with the Premium HDD navigation, traffic is via XMNavTraffic services which I believe has been discontinued.