Most of these just seem like basic educational issues except this one imo:

Every language has words for yes and no.

I want to see more than like 1 or 2 counterexamples. I’m pretty interested in linguistics on an amateur level. Don’t believe I’ve heard of that one before now.

Arabic doesn’t have a word for “yes”. I don’t think most semitic languages do either [Classical Hebrew does not, but Modern Hebrew does, however, the word they use in modern Hebrew is the word for “Thusly”, that is now a particle]. In fact you can see that proto-indo European didn’t have a word for yes: Greek is ναι, but the romance languages are si (I am pretty sure French oui is actually derived from the same root as Spanish and Italian. Could be wrong) and if my memories is correct (and it may not be) classical Latin didn’t have a word for yes. And the Germanic words yes/ja have a similar origin. I can’t speak to the other IE languages unfortunately.

I know there are also language families that don’t have a single word for no, but use a negation mood on the verb. I unfortunately can’t give you an example of this. But it should be fun to look up!