There has been nothing suggested that the 60-day exempt entry is temporary. Of course you can guess, but why would anyone base a strategy on guesses made on Facebook? The change was introduced to increase foreigners in Thailand, spending money and contributing towards the economy. It's by far the best option for someone who comes and goes frequently and spends a lot of time in other countries, as that is a true tourist
I think it's best to remain silent. If the Thai Tax Office wishes to carry out an audit (Probably a million to one chance), you simply produce the Tax Paid document from your home country, work out the difference with Thailand, deduct the allowances, and put out your hand and request the Thai Tax Office gives you the difference 😂😂😂
Unlikely you'll need to file a tax return in Thailand if you have already paid tax on your "remittances" as differences would be so minimal it would easily be covered by the deductions. If the Thai tax office enforced this detail, they would be inundated with forms which ultimately would cost them several thousand baht to process with nil return
No there isn't, it's based on a number of factors, all of which are ambiguous. There is a proposal to tighten the criteria which at its base will be Australian Citizenship and 45 days in the country in every two year period. It's extremely easy to maintain residency in Australia.