to which airport should i go from beijing to jiamusi ?

From Beijing capital airport, there is direct flight to the local Dongjiao airport, you can take that. Upon arrival, you are suggested to take a taxi to your university, and the fare is about CNY30 – 40.

which hotel is nearest to the university and what abt the prices?

Well, what's your budget about your accommodation?
You can go to Qianli Express Hotel. It's about 0.7 miles away from your university.
The price is around CNY 150 per night. This hotel provides clean living environment. It's located at 529 Zhongshan Street. Hope you like.