As far as who was the first woman to play in a symphony orchestra, Florence Wightman was the first to be principal harp, in the Cleveland Orchestra, but Edna Phillips was the first to be principal harp in a major orchestra, as Cleveland was not considered major then, and I guess Edna and Alice Chalifoux must have started the same year. There were harpists who subbed, played second, free-lanced before that, including in the Sousa Band. It was perhaps in the 40s that women began to win more seats, particularly when Salzedo began to graduate a lot of them into orchestral seats. He had fewer male students, but Reinhardt Elster at the Met, and Ed Druzinsky in Chicago count for something.
What does matter is being able to play with strength and command that blends with and matches all the other players. As my teacher, Lucile Lawrence, put it: you have to be able to play the harp like a Man to make it; and that would apply to everyone. (Orchestrally speaking)