Excellent story, it seems that previous reviewers touched on those subjects that I wanted to comment on. Except for one.
I believe that it goes "The needs of the many out WEIGH the needs of the few." normally I believe such a mistake could be done in character since fictional characters should make mistakes with sayings about as often as the authors. And it doesn't bother me unless it comes from characters who are considered above average in intelligence(such as canon Hermione, your Hermione while smart would consider such things trivial)
Author's response
Yeah, well see, William was quoting a movie he'd never seen from memory, and used the homonym. Yeah, that's it. It had nothing to do with my fat fingers and not proof reading properly...