Travel / Recommendations for a stay in Krakow? January, winter. [5]

Cześć everyone!
I will visit Poland on the 8th of January. I will participate in a youth exchange for 7 days and organization will take place in Poronin. I will spent almost 2 days in Krakow so where do you suggest me to visit? -I will definitely visit Old Townand Kazimierz- :)

Are there any cheap hostels and second hand shops that you can recommend?
What about food? Besides zapiekanki:)
And is there any friend out there to meet up for a coffee&good conversation?
Thanks in advance!