I never stayed there or had anyone stay there that I know.
Its about 9km from the airport which is about 15-30min drive depending on traffic. Since it isn't close to the town centre, you should be able to avoid majority of the traffic.
Cab would be about the only way to reach it. I would guess somewhere about/under 40PLN (15USD).
No tube in Krakow. We have trams and buses, but from the airport there are buses which go to the city and a train which goes to the city centre and back to the airport. I think your stuck with the cab option.
The lines that stop outside of the hotel (from their website) are bus 172 and 130, but the site mentions its a good walk to them