Huh, I don't know how the queen would be asked, it would probably have to be worded in a very fancy way. Here you're simply talking to multiple people, with whom you're not on a first-name basis.
Yes, it's formal, but no, it's not the best form for talking to the queen (you'd want to use singular, rather than plural, which is the form here). Hungarian differentiates singular and plural in both the formal and informal.
If you are a customer in a (polite) shop you would be "ön" - so not just "official". But more distant. "Maga" is the polite form between equals - one doctor speaking to another for instance.
Hm, I don't think it would sound strange. There isn't a clear line between "ön" and "maga". For me, "ön" just sounds much more common (maybe a bit friendlier?).