The say-yes-when-they-mean-no thing is probably just a linguistic difference. In Thai, responses to negative questions usually refer to the statement in the question itself, not the fact; for example, if you ask someone, in Thai, “aren’t you going to school today?” and he or she responds with “yes,” it means, roughly, “yes, it is true that I’m not going to school.” It’s a little confusing, though, if you respond with “no.” because that could mean either “no(, I’m not)” or “no(, it’s not true that I’m not going to school.)”, but the next utterance and the context will most likely clarify everything.
As for the rest, well, I don’t know who you mean by “we” in your “…we don’t,” but I believe a lot of non-Thais do those rather negative things you’ve mentioned, especially the second (Have you really *never* heard of “[Insert a child’s name here], put your phone down!” in any movie’s scene at a family’s dinner table?) and the fourth. Being an internet addict or a show-off is not in the blood.