does window of the world open during chinese new year, 13th-14th Feb?

Yes, it is open during that time, so do not worry about it.
I know a very good mulism restaurant there. It is the restaurant of Muslim Hotel, which is very close the local train station.
If you are staying in Golden Central Hotel, the restaurant is a little bit far away from your hotel, but you can take a taxi to reach. It is worth trying.