1 - Since its confirmed to be ~11 minutes I think that it might either go up to only half of Act 1, or a heavily condensed version of the full of Act 1
2 - I have faith that it will be good.
3 - This is distinctly a pilot and not an "episode 1", which I will say is an important difference because a pilot is mainly intended to gauge interest in a full series. I believe that Karkat and Jade's presence are a liberty taken for the reason of this being a pilot episode- giving teasers of some of what to expect, primarily aimed at hooking in casual audiences. I think the AH author sona inclusion is probably something to do with this as well, likely to tease the meta narrative element of the series.
4 - As previously mentioned the pilot is 11 minutes according to the Animate Orlando panel it was announced at. But a potential full series I think could potentially be done in 4-5, maybe 6 seasons? I've heard that the proposed plan includes a rewritten/shorter version of Act 6, so I think something like S1 = A1-3, S2 = Intermission + A4, S3 = A5A1, S4 = A5A2, S5+6 = Act 6. This all depends on the pacing, the lengths of episodes, and how long each season is though. This is just what sounded nice in my head.
5 - Rapping scenes, duh!! Them licensing How Do I Live or I Don't Wanna Miss A Thing would also be extremely funny though.
6 - Honestly, I see a 50/50 chance of this happening. I don't see content farms use vivziepop characters nearly as much as like Digital Circus or Friday Night Funkin. Its very plausible that Homeslop doesn't happen, but it also very plausibly could. Only time will tell.
7 - I think they will think its pretty cool. I looked up some reactions from people who were like "idk what this is but this looks neat!". I think it'll probably be divisive among Homestuck fans and some people will continue to be really really annoying about it like they already kind of are being online, but I think overall the outside reception will probably be positive.
10 (where'd 8 and 9 go? did 7 eat them?) - I like it! I think some people have been too nitpicky of it but I think its nice so far. The backgrounds and the art style are very like cartoon network-y and I think that's cool. I still think the fact that Homestuck characters having "official voice actors" who are industry people who play other well known characters is something I am still not used to, I'm not sure when I'm going to be used to that. Imagine going to a convention and the guests have a Homestuck character on their banner next to like famous anime and video game characters, like what the fuck. The casting announcement for Richard Steven Horvitz playing Caliborn in the Act 6 cartoon adaptation is going to be insane. Honestly won't even be surprised if he ends up playing some random other extras before then like Eggs and Biscuits from the Felt or something idk. On that note though, that brings me to the one thing I am most curious about, and that I also submitted to the Q&A:
I am SO curious how they will adapt all the dialogless characters. Like, they don't have "dialog" but they aren't characters who can't speak. Will there be an external narrator, will all their scenes be internally monologued, or will they be fully voiced with speaking scenes?? The idea of the Midnight Crew audibly speaking to each other is cursed but... not wrong?? Like they do talk to each other but we don't read it directly. I just want to see the Intermission episode more than anything, really.