I cani vedono in giallo, blu, e grigia. :)
EDIT: Fixed year-old typo "griga" instead of "grigia".
Duolingo has a strange idea of the Italian word for blue. In everyday speech, I'm fairly certain that people say "blu". It's the normal word for blue. But for some reason, Duolingo teaches you "azzuro" which is a type of blue, or sort of a fancier word for blue.
Yes, but the order in English is always "black and white". To sound right in both languages, the three-word phrase "bianco e nero" effectively translates as a single chunk, into the three-word phrase "black and white". Applying the correct idiom, rather than word-for-word literal meaning, is part of learning the language.