I only got into Homestuck a couple years back, but off the top of my head:
CASCADE, MEGAPAUSE, GIGAPAUSE, ...WHATEVER THIS FOURTH PAUSE IS CALLED: Hussie was known for an incredible update schedule, sometimes multiple times a day. However, there have been some long pauses. You probably remember Cascade, the amazing 15-minute flash. That took about two months to make, during which there were no updates. Considering Hussie had never taken a break longer than two weeks, weird stuff started happening to the community. In 2012, Hussie ran a very successful kickstarter for an MSPA game (which eventually materialized as Hiveswap). However, doing game stuff took more of time than he anticipated, and he Megapaused for two months in 2013 to get that done. The community went insane and started hemorrhaging weird sprite edits. After those two months were done, there were sporadic updates until late October of that same year, at which point he announced the Gigapause--a hiatus with length unknowable. The game and various other projects were really eating into his time, and the story was edging into endgame; he wanted to deal with all his projects, work on HS, and then post it all at some point in the future. The pause was so long, the community (which had always been very vibrant due to the rapid updates) started drying up. Then, in October 2014, he started it again. He STILL didn't have quite enough time, so we had scheduled updates until this most recent january, at which point he announced our most recent pause which will last until 4/13.
THE PIXEL THAT SAILED A SHIP: okay, this didn't make an enormous splash, but it's a good example of how the author-community dynamic works. This page shows Dave talking to Jade with a single-pixel smirk. Hussie later stated that this was an experiment on the community: how little information could cause them to start shipping two characters? I just find it interesting because it's a move by the author not to do something to the story, but to do something to the people reading the story.
MURDERSTUCK: Vriska kills Tavros, Eridan kills Feferi and Kanaya, Gamzee kills Equius and Nepeta, Kanaya comes back and kills Eridan, and Terezi kills Vriska. Okay that's probably too wide a swath to paint for Murderstuck, but it was before my time. Essentially it was that spate of troll-on-troll murders in late Act 5 Act 2. The community was floored and horrified, not just by the deaths of important characters like Kanaya and Vriska, but by the rapid reduction in living cast members. Some people had also grown very attached (somehow) to bit parts like Equius and Feferi. Hussie had (kinda sorta maybe) killed off characters before, but this was what probably solidified his reputation as a George R. R. Martin-esque committer of ficticide.
THE TRICKSTER ARC: reading archivally, Act 6 Act 5 Act 2 goes by pretty quickly. However, serially, it lasted two weeks. That was a long time for fans to be checking the site every day and finding garish colors and dancing fruit gifs. Some grew impatient with it. Sorry, this is pretty small, but I think the difference between archival and serial reading--especially how Hussie started prioritizing the former over the latter, sometimes to the detriment of the community--is interesting.
SUP: this page was at the end of one particular update. Originally it had flavortext from an earlier version of the same page. This combined with Roxy's seeming unresponsiveness led to many theories that she was somehow broken, like a glitched NPC. However, the next few pages at the beginning of the next update quickly disprove that. Sorry, this is like the smallest thing on this list, but again it shows something about the community: how it tends to overblow everything in an update because that's the most recent and relevant information it has.
Wow that was a lot of words, but I think it was an okay cross-section of MSPA and the community reaction to it. Good luck with your podcast.
