when would you use "kun" instead of "bare"?
kun means only and bare means just. In many cases you can say both things, like in English you can say only a boy or just a boy. Likewise you can say kun en dreng and bare en dreng. Just depends on what you wanna express with it.
no no no no nooo your son can be nonbinary, a female, stay a male, and MANY MANY more things.