"The boy has oranges."
Translation:Der Junge hat Orangen.
Not everywhere: http://www.atlas-alltagssprache.de/runde-2/f07a-b/
(For the benefit of anyone planning to visit the south, where it's not common)
True, but Apfelsinen is still a valid translation and very common among Northerners.
No, not on this course.
In my experience, it's... not exactly rude, but perhaps a slightly coarse word for a boy. More like "chap" or "fellow" or perhaps even "lout".
It's possible that in some dialects it's the normal word for a boy, but not (in my experience) in standard German.