Violet, definitely Violet. May adores the idea of cooking, she really does, but also she's horrible at it. Almost as bad as Della levels of horrible (still not to the point of June, though). She has almost burnt the house down multiple times because she's snuck into the kitchen to cook something.
Violet, meanwhile, is a very good cook. She wouldn't be very happy doing it for a living, but does get compliments along those sorts of lines commonly.
14: Who is the highest maintenance? Does the other mind?
Depends on what one considers 'high maintenance.' Because Violet's complete lack of morals, understanding of just enough of the arcane to get herself into trouble and not get herself back out, and sheer, almost wizardly levels of hubris (do not get me started on how I feel about wizards) tend to lead to some very world-endy type scenarios. May doesn't mind, though. She's always down for some world-ending shenanigans.
But even with that- May is probably the higher maintenance one. Because, well, trauma. She was literally created to be a killing machine/Scrooge McDuck's heir, her entire life was spent training and learning under two of what have to be the most abusive motherfuckers in the world (save Magica), and she was forced to watch as her father literally killed her mother.
On top of all that, she's constantly learning new things about the world, has no idea how most common things work, has the strangest patchwork of knowledge, and has pretty bad anger issues. She's high maintenance as fuck.
But Violet doesn't mind. She knew what she was getting into when she became May's friend, let alone lover. She tends to make sure May gets the best help available, and not just that she helps her. That often means going to others and requesting that they aid May in her stead, even though she would love more than anything to be an expert in everything, just so she could be the person May turned to for- well, everything.
But she knows that's not healthy. And she wants this relationship to last, so she strives for as healthy a relationship as she can manage.
11: Baths or showers? Together or separate? Any bubbles or bubble fights?
Just based on a first glance, you'd suspect that Webby loves baths and Lena prefers showers- but you'd be wrong.
Webby much prefers showers to baths, she feels a lot more prepared with them. They can be quick, and brisk, and she always takes really really cold showers which everyone freaks out about when they learn. (Her penchant for cold showers is partially because she's a health nut, and partially because Scrooge is stingy as fuck when it comes to the heating bill, so she learned from a young age that cold showers meant she got to stay in the shower longer.)
Lena, however, prefers baths. Long, warm, constantly filled up baths. I mean she never really got that luxury when she was dealing with Magica, after all. Plus she never really got to be alone. But when taking a bath, she can put some music on, curl up with a book (without Violet looking over her shoulder and spoiling the whole thing), and just vibe for a few hours. Granted, she also needs to put a silencing spell on the door so her family's pounding and demands for her to get out because they also need the bathroom doesn't distract her, of course.
So for these reasons (Webby likes quick cold showers, Lena likes long warm baths, Lena likes the solitude that comes with being alone, Webby gets a little squicked out at the idea of swimming around in water that's supposed to be cleaning her), the two don't tend to take baths/showers together.
Well that and one other reason. (Any time they do they get a little... rowdy. Which isn't very good for getting clean.)
That being said, the few times Lena has convinced Webby to take a bath with her, it's always ended in a bubble fight. Because of course Lena takes her baths with bubbles in them, she loves bubbles. They remind her of Webby.
15: Vacation ideas: who decides them? Where would they go, if anywhere?
They both love coming up with vacation ideas, they both have very different ideas with what constitutes a 'vacation.' Lena always wants to go somewhere quiet but expansive, like the countryside of Italy or the Swiss alps or something. Webby loves the idea of danger, and is always trying to get them to go either to amusement parks or to actual ancient ruins to get themselves cursed.
Violet usually has to be the one to decide for them, because they'll end up never deciding on their own.
And ultimately they'd travel the world eventually. They've both been to a lot of places, after all, but they've never really seen anywhere. So they'd love the chance to just take it (kinda) easy, and see what it's like to actually experience the world as its meant to be experienced.
And if they end up getting into a few magical mishaps along the way, well... I mean it's Webby and Lena, what more could you ask for?