Looking for some help

Hello! Recently I started doing some digging on Ancestry.com to find out as much as possible about my Norwegian ancestors that emigrated to Wisconsin in the late-1800s. I want to visit Norway someday soon & I think it would be amazing to visit any locations where my ancestors may have lived, worked, gone to church, etc. I’d love to know anything about their emigration route as well, if possible. I believe I’ve struck a bit of gold already...my great grandfather’s brother Henry, on his WWII draft registration card (that he filled out at age 63), listed his birthplace as “Modem County, Norway”. I’m assuming this is probably Modum in Buskerud county? I’ve started doing some digging on the Arkivverket site with all of the info I have, but it’s been a bit daunting & I haven’t come up with anything so far. I’m wondering if anyone might be able to point me in the right direction? This is all of the info I have from Ancestry.com. I'm not sure how accurate the exact dates are. It’s mostly from censuses in Washburn & Bayfield, Wisconsin, 1900 - 1940: Father: Thomas Thompson b. Apr 1855 Mother: Thora Thompson b. Jan 1854 Son: Tom Thompson b. Dec 8, 1876 (my great grandfather) Son: Henry Haldor Thompson b. Nov 30, 1878 Son: Hans Jacob Thompson b. June 16, 1881 Daughter: Hilda Thompson b. May 1884 Son: Thomas Thompson b. 1887 The immigration date on the 1900 Washburn census is 1889 for the father, Thomas Sr., and 1892 for the mother, Thora, & the children. So he may have come over first & then the wife & kids a few years later? Also, my father is pretty sure he was told at some point that our surname was originally Torgesen, but he is unsure of the spelling. And also that my great grandfather, Tom (the oldest child) may have originally been named Thorval. That’s all I know as of right now. Any help on where, if anywhere, I can go from here would be greatly appreciated!!