I would have replied to this right away, but I was kind of at a loss for words. I still am! I am deeply honored!
Fanfics with far more words, readers, and reviews do not get this. My gold standard of fanfic popularity -- Harry Potter and the Methods of Rationality -- did not get any until chapter 53, and Eliezar has much longer chapters than I do!
As to the issue of who knows whom, for my purposes Tonks has not introduced herself to the twins yet in this timeline, although she does in the next chapter I will post. As to Fred and George, it is not yet clear to _them_ that skills useful for juggling and food fights are also useful for dueling. Eeles doesn't realize it isn't obvious to other people, and so says nothing, and Dumbledore has his own conflicted reasons for not saying anything either (he is deliberately training them to fight, but doesn't want to spoil their innocence, more or less). The twins probably can't get to the level in your story until the end of the year at the earliest -- I'll explain why once the story gets to Christmas. Otherwise, it's exactly the sort of thing I think Eeles would do. :)
Author's response
Argh, that was supposed to be a response to another review!