Find a place. Work out how much youre paying for cabs/public transport over a month. Work out if that will be normal usage. Compare that to cost of car and fuel. Job done?
yes but you could buy your 90 day ticket but still get "onward travel" proof for 60 days so you then don't have to pay to change your original, more expensive flight
You can extend but you'd have to match O visa requirements, so cash in a Thai bank. If you wish to get a second year from your o-a then a border bounce within 365 days of the visa being granted is required