How do you tell the difference between definite (the cook) and indefinite (a cook) nouns?
You cannot because that concept (a, the ) does not exist in Swahili or any Bantu languages.
As far as I can tell, it's just contextual.
You can point to a specific cook, like mpishi yule (this cook)
I cannot keep the second and third person words straight, aside from "sisi." For example, I am always thinking "yeye" is one of the "you"s. Does anyone have any tips?
But Yeye can be used towards men too? So it goes both ways?
Is yeye ni mpishi not 'she/he is a cook' I'm told here it's is she a cook?
It is both, the difference is the question mark. With the question mark, "yeye ni mpishi?" can be either "he is a cook?" or "Is he a cook?" because we can phrase this same question different ways in English.