I think little glances were good and made it more real-like a dream. The back story added to the film by making Ichabod more real but it wouldn't be necessary to make it more detailed!

I think exactly the fact that they aren't here make those scenes realistic, like actual childhood memories, the story becomes clear anyway, but flashbacks really look like exactly what he remembers - sees in his head and dreams. Like who would remember such details as conversations from very old childhood memories?