The father's name is Tzvi Yosef and he was called Hirsch or Hirsch Yosef. Tzvi and Hirsch both mean a deer in Hebrew and Yiddish respectively so they are often used interchangeably. Shimon is the son.
Gershon and Zussman do look like the correct names listed for the groom's brothers. Regarding the name Zussman I agree it's not so common as a given name, but I did find it or similar names (Ziskind) online. It means "sweet man" in Yiddish and seems to be a nickname connected most often with the names Eliezer, Alexander, or Shneur.
Hope that helps,
Binyamin Kerman
Baltimore MD