If Quinn sent the letters... Then its implied that Tommy gave her the pictures but that is out of character for both of them. Quinn is trying to bring the HOTs and the DIKs closer together and Tommy may be an asshole but he is loyal.you're right, everything is connected, but, to give an example, who sent the letters with the pictures to the Jocks at this point of the story is not so important anymore, in the same way who devastated the DIKs house
or must be an unsuspected, which then changes our way of considering a particular character, or otherwise it will still be someone who regardless of his guilt was already definitely a villain of the story (Quinn? Vinnie? Burke?).
going back to the interlude: it has to give substance to Zoey's character, who otherwise would be a foreign body in the story, the fact that we have been told that she was the first fuckbuddy o
Vinnie is the best option and makes a lot of sense but DPC likes to shock people so my money is on someone unexpected, even if It makes less sense. Lets hope he doesn't do that in the future.
About the interlude, It would be awesome if Zoey ends up being close to Vinnie, that can be a great way of introducing Vinnie and a challenge to Dik players since they would maybe be forced to choose between their long lost love and friend or Quinn since Quinn and Vinnie's story will clash.