Please tell me the best way to take the train from DUS to Colonge's main train station. Are there two train stations at the airport ? I'd rather not change trains. I understand there is a Sky Train to take me to the train station. If I buy train tickets before boarding the Sky Train, is the Sky Train free ? Thank You.
If you purchase a VRS ticket for 11.30 EUR to Cologne Hbf, the Sky Train is included to the Fernbahnhof. You will need to travel only on the regional train to Cologne, not an IC or ICE train. If you have 4 or 5 people, get an NRW group ticket for 42 EUR. That will also include any other local travel in Cologne for the rest of the day.
You can also travel on the S-11 direct to Cologne from the Terminal S-Bahn station, but it takes 1 hour and 20 minutes because it has to make every single stop between there and Cologne. The regional trains from the Fernbahnhof do it in under 40 minutes in a bit more comfort.
You only need to pay for the Sky Train if you are traveling on a regular Deutsche Bahn ticket using the IC or ICE trains. Then it is a VRR short-term ticket for 1.60 EUR bought out of the vending machine on the boarding platform.