It's simply not possible to live in Thailand long term using just visa exempt entries or tourist visas any more. It's got much more difficult since visa exempt moved to 60 days in July. People are regularly being denied entry. You need to get a visa that's appropriate for your stay
your countries tax office will send it to the Thai tax office once a year but it will have all relevant information from across the year including debit/credit card transactions
if you are paying by non-Thai credit card and then clearing the credit from income that's equivalent to bringing the income in directly from a tax perspective
not true. From a Thai tax perspective it's a total of 180 days or more in a tax year. The only thing that resets the clock is moving to a new tax year.