So how do they get down? Jump? If the rockets are grounded. Do they have a craft docked to the station they can come home in?
They have a Soyuz capsule at the ISS as an emergency lifeboat.
There are two Soyuz capsules docked to the station, they serve as lifeboats for emergencies, and will be used to bring crew back. No one is stranded, but they can't get new crew up until the resolve the issue with the Russian launcher.
“So how do they get down?”
According to Wiki..
As of 23 August 2011, there are 3 spacecrafts docked with the ISS.
Russia Soyuz TMA-21 Expedition 27/28
Russia Progress M-10M Progress 42 Cargo
Russia Soyuz TMA-02M Expedition 28/29