Given that the first person pronoun has three numbers (when inclusive), the sue of " 'oe" as you, without making clear how many yous are involved, is a bad, and confusing, act.
Modern English (wel, most dialects of Modern English) use "you" for both numbers. There are a few dialects that preserve the archaic singular "thou", and others that have created the "you all" (and variants) for the plural, but they are far from mainstream.
Even if 'oe does serve for all numbers, it would be a very good idea to explicitly state this is the case. If we misunderstand this word when we first meet it, we are likely to keep on getting it wrong later on.
"Maika'i 'o ia" means "He/She is well/fine". "Maika'i 'o ia?" is a question and means "Is he/she well/fine?" You recognize it by either reading the question mark or in voice, listen if the voice gets higher towards the end (=question) or if it goes lower (= not a question). Hopefully my reply is somewhat understandable.