I'm Swedish so love what you're doing, however I don't think I've ever seen a "kakelugn" in the middle like that when it is partially round. They generally go in corners and rectangular ones go flat against a wall. Though you might be able to make it work since the base is rectangular. Just make sure to install it against the wall and not floating or sticking out too far. Unless of course you don't care about being authentic.
Here's lots of pictures of "kakelugnar"
https://www.google.com/search?q=kakelugn&client=firefox-b-1&tbm=isch&source=iu&ictx=1&fir=rwXemerbDV6XGM%253A%252Cw_WUtxBRWR4fDM%252C_&usg=_JLYZqMJixFNRPHYrD7eQeH6SI3c%3D&sa=X&ved=0ahUKEwjYrP_Z7bfZAhVs8IMKHbBhBMQQ9QEINDAD#imgrc=
As for colors I think anything will be fine from a Swedish style except beige. Don't remember seeing anyone ever using beige growing up or now for that matter. Wallpaper is very common, although I think paint has grown some though wallpaper is still very popular. White is a very common wall color if painted. Gray is also not uncommon - although I've never been a huge fan of it as it is so gray outside for much of the year. Pastels or lighter colors vs. saturated would be more likely uses inside. Saturated though is common for the outside. A deep red, bright blues, grays, bright yellows, pink, greens, black, are all used on the exterior as well as white. Generally the exteriors tend to lean towards "happy" colors as opposed to grayish or tan.
Blue walls would be just fine IMO.
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33x8,5
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