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
if he wants a second year on the o-a then he needs to re-enter before that expires as that is valid 1 year from issue. If he first came 1 month after the visa was issued to get a second year would require exit and re-entry after 11 months