Given how long it took Sage to mentally process the news about Troy, I doubt Jade specifically thought Chad was gay. My guess is that Jade thought Chad was only using Sage for prestige or sex, and so she warned Sage not to get too attached to him. (As I recall, Sage mentioned that possibility right after the breakup.)
First off, I don't think they really were blackmail letters. Chad thought that when he attacked the MC, but as he himself admits, he wasn't thinking clearly at the time. Unless the letter told Chad to break up with Sage (which is difficult to square with the Mel & Sarah scene if the MC is on Sage's path in Episode 5), Chad doesn't seem to have done anything that would take blackmail. Also, unless Chad secretly removed a separate letter for Dawe, his letter contained nothing but photos of DIKs banging Arieth. Given that everyone knows Arieth is sleeping around, that's about as far from blackmail as clandestine envelopes get.
Personally, I'm think the most likely theory is that someone either wanted to piss of Dawe and Chad, or wanted to stir up trouble between the DIKs and jocks specifically. The question then is who would do it? Troy could have been a good candidate before we confirmed he's Chad's secret lover, but he's out now. The nerds might have the capability and a general motive, but there's nothing in game that links them to the pictures. Vinny might want to stir up trouble, but it's unclear how he would know about Chad's secret. Sarah and Mel do know about the secret and clearly have an agenda, but the look between Chad and Mel make me think Chad knows they know, which would make the letters pointless. I even tried to examine the timeline once to see if anyone was suspiciously absent when the letters were delivered, but sadly the scenes at the start of Episode 3 are so out of order I can't even be sure what scenes are contemporary.
Unfortunately, I think this is one of those mysteries where we don't even know enough to speculate meaningfully. Which is definitely frustrating given it's been languishing for 5 episodes and counting.
Ugh, no side projects, please. Every minute DPC spends on a tie-in is another minute we have to wait for the actual game. If he needs time off to recharge, that's one thing. But if he's going to spend time on BaDIK related material, I'd much rather it be the game itself.
As fort he GoG announcement, I'd say it's exciting for the folks who'll be introduced to the game via the new platform, and that's a good thing. I'm also always happy to see more competition for Steam. But I'll agree I'd much rather learn a bit more about what he's planning for this Interlude...
You need to have 6+ DIK reputation points when the time comes to crunch the numbers. If you have 5 or fewer, Rusty sells his car. [EDIT: This is assuming you disabled mini-games. With mini-games on, you just need to buy the windows for $65 and finish repairing the mansion in time.]
According to the official walkthrough, you also need to have turned down the VIP pass, but I have not been able to confirm that last part myself. And personally, I don't see why you'd want the VIP pass - especially on a non-mini-game run. Where the hell are you going to find that kind of money?!?