Looking for info on Hans Kostad

Hello I am trying to find some information on my great-grandfather whose name was Hans Kostad. He was born in Norway and my grandmother said that he came from the area of Christiani (now Oslo I believe). I know that his fathers name was Nils and on the grave his last name is spelled Kaastad. Hans is buried in Lignite, North Dakota, but I'm not sure if he went straight to North Dakota when he came or not. I would like to try and find out what his mothers name was and if a family list or list of members in his family or a least living on the same farm could be found. Hans's father is also buried in Lignite, North Dakota, but I don't think his wife ever came to America, she possibly died in Norway. Any help would be appreciated! -Tim Larson