I just tried the steam demo today and I really enjoyed it even though I was disappointed that I didn't get to meet Maaku since she's the character that interests me the most.
To answer your list in order:
-I took my time playing whilst doing other things but I finished the game in about 2.5/3 hours
-im fine with the way it currently is but, generally, idle animations seem choppy and too fast/exaggerated.
-I did, I like the ludo-narrative implementation of this setting. I'd be nice to have to option to change it later on, maybe by talking to Os again. The scene with Os was expected and did not bother me but the next one was very unexpected.
-The volume was fine but I was annoyed that the music occasionally stopped for long periods of time.
-Even though you barely get a glance of her in the demo, Maaku is the character I'm most interested in. I guess it's partly because of her appearance and what I expect her to be like because of it. (confident, bold, adventurous, proud, playful, kinky, dominant) I'm sad that she seems to be a side character, I hope she'll have a good amount of content.
From the characters I was able to meet long enough to form an opinion, Kyta was my favorite. I enjoyed her playful mischief and she really felt like an alien being. Sho also seemed interesting but I don't care much about the other 2 main characters so far.
To end on a good note, the game has potential, keep up the good work!