[spoiler]I'm uncomfortable with the big villain being a witch who was sentenced at the Salem witch trials. It legitimizes the trials.[/spoiler]
Edith seems improbable. Someone as selfish as she seems to be... would she have married Gabriel? ... and it must have been after the accident, which I think happened when he was a kid. If she married him for the money, then she's been awfully patient all these years, especially since Quentin was obviously going to get it. But then Quentin was on Gabriel's side, sort of, and would have been generous.
I should remember that (1) marriage was considered permanent no matter how badly it turned out, and (2) people can change a lot over the years, embedded in nasty life situations. Edith may have started out kinder, and she certainly seems to be a better person in 1897. Well at least more clever.
Edith seems shoehorned in to maintain continuity, so Grandmamama is there in 1897. Considering what happens later, they almost needn't have bothered...
For Gabriel, the waiting is indeed the hardest part. At the end, when Sam walks in, nice shocked weasel look on Gabriel's face...