Facade paint - no agreement in sight...

too dark but also heat-sensitive

a gray-brown-beige looks somewhat Mediterranean, but with dark windows not bad either and is not white!

We (well currently only me ) are also thinking about faschen ...

too dark but also heat sensitive

Yes, I wouldn't go below an HBW value of 30 and would prefer a "Cool Pigments" material for a darker color, as it reflects the infrared radiation portion, which is crucial for heating up.

Without a house and surroundings, good advice is difficult. Playing with color, for example with a light base color and strong accents, can look wonderful with more or less simple means – e.g.

[*]Accents around the windows
[*]Lines that visually stretch horizontally or vertically
[*]Suggesting shadows
[*]Strengthening or letting contours disappear
[*]Connecting or separating surfaces
[*]Connecting inside and outside (e.g. emphasizing a functional area)
[*]...

Gray stripe on gray background, great contrast.

There should be more than just one shade of gray

You can simply use a search engine: gable roof, gray-brown facade
Looks very modern. For example, I've gotten a bit tired of the white/anthracite contrast.
But it's a matter of taste and, of course, the question of what fits the style of the house.

We faced a similar question. We have now decided on a light gray facade, a dark gray dirt stripe, white windows, and an anthracite-colored roof and front door. I'm more of a brick fan, but my husband insisted on plaster. And it was clear that I definitely did not want a white one. We initially wanted the windows in a moss green – but for me, it wasn't worth the extra cost. I will spend the money well elsewhere.
Gray windows with a white facade were immediately out for us, by the way – almost every plastered house here has that. Then rather with a red roof. But in my opinion, that looks silly with a photovoltaic system.
In the end, you decide to the best of your knowledge and conscience. And then you live with it. If you constantly think about alternatives that in hindsight maybe and anyway... that will wear you down in the long run. It starts with the facade, goes to the floor plan, and ends with the flooring. No thanks. So look for what feels best to you in your gut (especially also see many houses live!) and then be done with the decision.

What color will the patio slabs be?

that is always a matter of taste. Your shown house with a light gray facade looks like a modern country house style, a white house with dark windows appears more modern and elegant. It also depends on how the rest is designed, for example [Garagentor] and [Zaun], it should all match together.

Best regards
Sabine