Hi Steffy,
I know the Championship. Once it was organised at my university, or Koc University, at 2005, and the attendees were excited to participate it. and you will have a great time. Best wishes at Championship
One of the most beautiful city to visit in Turkey is Antalya, but in Jan you have to cross from your list to go beaches and to attend sea tours which are the most enjoyful activities in city

The weather does not cold, it is moderately warm and rainy. Be prepared to unexpected rains. If you want to go inside cities like to visit Pamukkale in Denizli from Antalya, the weather becomes colder. I recommend to see Kaleici, historical center of Antalya. There are a lot of things to do, I think the organizators will take care of it. But I advise to eat Turkish kebabs & deserts as much as possible
Enjoy Antalya!!!