send me a ship and I’ll tell you who:
It would honestly probably be Maliris, if only because she wouldn't trust Kraken to do it right. But then, because Maliris wouldn't buy anything constituting real food, Kraken would have to go out afterwards and actually buy food - without Maliris noticing, because she'd just get offended.
Both of them, unless the spiders are near enough to a door to be safely escorted out. ...Maliris would be the type to chase Neirin around with a spider on a napkin, though, so there's that.
...Both of them. With Tiamat.
Neither of them is particularly good at cooking, but Maliris is more inventive and experimental. Honestly, they'd probably both make breakfast, bickering the whole time, and the resulting meal would be... reasonably edible, if not necessarily enjoyable.
remembers to feed the fish
That would be the Water Guardian, Kraken. Naturally.
Surprisingly enough, this would be Maliris. She believes in bright colors and decorations. Kraken likes to decorate herself, but prefers calmer, quieter surroundings without a lot of flash and clutter.
This kind of depends on what you mean by "duet." I can see Kraken trying to strike up romantic duets as they walk or sit together, that sort of thing, and having to coax Maliris into it... but on the other hand, I figure once they get drinking, Maliris would be the first to launch into some bawdy tavern song.
Maliris, but she's a light sleeper.