There is no 100% correct national requirements list because the about 90 individual immigration offices can add their own requirements. Thats why we always advice to contact your local immigration office.
If someone want to be on the mercy of the I.O all the time it's ok. There is still a risk a I.O is not so considerate. But having the proper visa is much better. I remember covid when all who did not bother before to get a visa where stuck outside. eventhough they had property, wife etc. Properly living in Thailand but no status. i think thats not wise.
Thats not fine. Read the post. Immigration started to question the OP. That happens more often if someone has many visa exempt entries and seem to be not a 'normal' tourist. They mostly start with a warning sugesting to get a proper visa. Its something not to ignore. You not want to be red flagged if yours wife and kid(s) live in Thailand.
As a general rule an onward ticket is not asked for or a requirement for anyone on a visa. It's specifically appropriate for a exempt entry. But a airline can still ask for it. Most likely not.