Oystein (Edward) Wahl

Hello. I’m doing some family research and am trying to track down the following information on my great-grandfather who emigrated to the States or Canada from Namsos: immigration records (where he landed and when), birth certificate and the ship(s) he traveled on. What I know: His name is Oystein (Edward) Wahl. He was born on July 20, 1895 (or 1986) in Namsos. He left Namsos in either 1915, 1916 or 1917. Upon reaching North America he went to the Seattle area first but I don’t know if landed on the East Coast of Canada or the East Coast of the States. After spending some time in Seattle he went to Alaska and then went back to Norway for a brief spell before coming back over to North America in 1920, 1921, or 1922. He came across both times with his older brother Haldor Wahl. Any information would be greatly appreciated.