See #2... "Travellers" 6 years and up are not exempted from #1. So they have to be vaccinated or tested. If vaccinated with Pfizer one jab is accepted for children under 18.
Nothing to do with Thailand Pass. If your country is listed for visa exemption then you'll get 30 days on arrival, this can be extended once for 30 more days inside the country. The Thailand Pass is just the proof that you fulfill the requirements like vaccination, insurance, test&go booking.
Normally they don't want to see it. Mostly your airline ask for it when you check in for your first flight. The point is that the airline is responsible to bring you back, if the immigration deny entry. So... it's better to have something to show that you will leave the country. If you don't trust this dummy onward tickets (although it works), just buy a real one with cost free cancellation.
The latest statement from government for reopening the bars was "not before 16th of January". That was before the Omicron panic. There's no way for a "best guess" right now, it's all just like this here... 😁