well, it depends... for hence, you can say "they are not men, they are boys" and it would be "eles não são homens, são meninos"
Thanks for the clarification, JPRoberto. Without a second half this sentence doesn't make sense because it starts with "eles".
If you see the boys, and you say "they are not men", you don't need to say the other part, what you mean is so obvious.
Homem, ending with an m, is the singular. To make the plural, we change the m to an n and add s?
Does "homens" always mean MALE people, and not men in general as in HUMAN? Is there a different word for "human"?
Does not always mean male people. We can use "homem" instead of "humans", but we normally use on singular. We can say "os humanos fazem mal ao planeta" and " o homem faz mal ao planeta" (without "S", if you use it will look you're talking of MALE people, sometimes
What if they are not all men? How should I address them? (Eles or something else?)
The grammatical default is masculine. Doesn't matter if you're referring to people or to things. If there are 99 people or things that are grammatically masculine and 1 person or thing that is grammatically feminine, then you use the masculine.