Question 9 imho is the most German one ("When someone says 'we should get coffee sometime,' you understand this to mean:"). It depends on context a bit obviously, but most Germans are sincere about it. You either propose coffee or you don't. However, there's a subset of Germans who seem to propose coffee and then don't follow up themselves, but it's not just a phrase. If you are the one to follow up, they'd join you.…
In that sense it does communicate something: I like and have enjoyed your company in this moment.
Flippant of course, but not too dastardly.