Surnames.........

If anyone caught the post I deleted, I have an American brain & we write our dates backwards. [:)] I'm sure questions like this have been gone over here before, but help!!! I begin with the surname Thompson. I was told it was Americanized, so fine, I'm looking for the Norweigian equivalent of Thom or Tom. Torge? Torje? Something else? Regardless, the ancestor's name was Torjesen, at least it was if it didn't include any non-english characters, but I don't know. But then someone threw a wrench into the works & told me an identifier for the name was Songe. Songe? I has to be a location, right? But I was told the location he was from was Holt parish in Aust-Adger, Norway near Tvedestrand & sometimes having info confuses, rather than making things clearer. Is there something like a sub-parish deal? Would Songe be a farm in the Holt parish in a town named Aust-Adger?