If you have Australian passport you don't get visa on arrival you receive 30 days visa exempt stamp which is zero visa just a stamp in you can get one 30 day extension whilst in the Kingdom for 1900 baht or get 60 day tourist visa issued in Australia and than 30 day extension give you 90 days or border crossing by land get another 30 day exempt entry but you are only allowed 2 land entries per year but there is no set regulation or law for the number of times one can visit the kingdom by air but any entry to Thailand is at the decresion of the IO infront of you at time of entry whether it be you first time or your 20th time it is looked at as if you are a tourist or you are trying to live there without the correct visa get correct visa for your purpose and you will have minimal issues Chokh di
You have until November 13th to activate your visa you will receive a 60 day stamp from your entry date if not activated by 13th November you will need to re apply for said visa
It's thailand and nothing happens fast in paradise and you need to adapt to thai pace of life remember even if you retire and live there it is still their country and if the house rules are not to your liking than find a house where the rules are to your liking nobody is holding you there simple π
My understanding is the only way a medical visa is granted is if you are in hospital on your death bed and unable to fly out of the country Chokh di with that one