안녕!! Welcome to Astana!
Firstly, don't be afraid of the weather. our climate is not wet and muggy as in Korea so the winter here is not so cold in the comparison with winter in Taehanminguk! Quite bearable. I know because ive been to Korea last year. Believe me winter in Korea was really cold even for me. You should just take with you warm clothes.
Secondly, as Jaming said you can bye sim card (Active/Beeline) in mobile phone centers. And you can supply ur mobile phone everywhere, even in small shops.
Thirdly, if you are an exchange student or a worker don't worry. There are Koreans in here, mostly russian lang learning students and also 한국 문화원. You can find a lot of Koreans and korean lang learning students over there.
You can find also quite amount of entertainment places. But comparatively with Seoul and Busan Astana is really small, anyway its a young capital with only 20 years history. Exept for the young generation and students people here don't speak english.So for adaption in the beginning learn some russian basic phrases (how to ask a road, or buy food).
p.s. after arriving contact me, i would be glad help you.
화이팅!!!