If I only knew this existed before today...
"Mysig" is the appropriate word, but it should be in the form of "mysigt" if you want to mix languages like that.
"Fika" is indeed at the core of Swedish people.
The things on his tray on page 21 are "dammsugare", lit. "vacuum cleaners", or punsch-rolls. Popular for fika.
Coffee with cinnamon rolls is the classic.
Yep, work-life balance is important. No undue overtime.
"The city rose with its 14 islands of various sizes next to Lake Mälaren."
It's probably more correct to call it in and around Läke Mälaren, as it's on both north and south of the lake, as well as on the islands.
"Ska vi fika?" would probably most accurately translate to, "Should we take a coffee break?"
If you've seen Kiki's Delivery Service and are familiar with Stockholm, you can absolutely see a lot of references.
It's common to double the "Hej!" (hello) in greetings. It can give a slightly friendlier impression, especially if you put a little melody in it.
I think Finland is the heaviest drinker of coffee, but Sweden's not far behind.
Very idealised, but that's expected with this kind of story. The city drawings are great.