you can do it by post but be aware that Canberra may reject photos because they do the biometrics from them and are really fussy. Best call the embassy for advice for shop in CNX
yes. Make an appointment. They were very helpful. Best to get your passport photos from the recommended shop in Sathorn. Hassle free that way. It is only 10 mins away by car/taxi/mc taxi.
I am sorry for my earlier stupid remark. My experience in Thailand is that the "letter of the law" doesn't always apply and these things are "fluid". But, you are correct. That is the law.