Short answers, pulled from the story.
Detroit had four NFL teams before the Detroit Lions: the Heralds (1920), the Tigers (1921), the Panthers (1925-1926), and the Wolverines (1928). The Lions arrived in 1934 when the Portsmouth Spartans relocated to the city.
The Detroit Heralds were founded in 1905 by a group of University of Detroit football players led by Bill Marshall, after the university stopped fielding its own squad. The team began as an amateur club and turned semi-professional in 1911.
The Detroit Tigers folded in mid-November 1921 because players complained they were not being paid and left the team during the season. The franchise's remaining players were transferred to the Buffalo All-Americans.
Jimmy Conzelman was a future Pro Football Hall of Famer (inducted 1964) who organized the Detroit Panthers in 1925. He served simultaneously as the team's owner, coach, and starting quarterback, and had previously played with the Decatur Staleys, Rock Island Independents, and Milwaukee Badgers.
New York Giants owner Tim Mara bought the entire Detroit Wolverines franchise after the 1928 season specifically to acquire quarterback Benny Friedman. Mara immediately deactivated the franchise and moved Friedman and other star players to his Giants roster.
Yes. All four of Detroit's pre-Lions NFL franchises played Thanksgiving games between 1917 and 1928. Results ranged from a 7-0 loss to the Canton Bulldogs in 1917 to a 33-0 Wolverines win over the Dayton Triangles in 1928.