not good for travelling to any of the island that time of the year that's why the flights & hotels are cheaper because it's rainy season (monsoons) its not good idea to be in or on the water big waves & strong currents.Come November-May worth spending the extra cash to have a good holiday
I wouldn't normally recommend using an agent for anything but maybe for opening a bank account as its a very time consuming thing to do and costly if you have to take out banks own insurance
Use Bangkok Bank or Yellow bank as you can deposit more than 55k at a time and they both expect Wise international transfer which show on your statements
Immigration are just trying to get people who are abusing the tourist Visa with extensions and going in and out the country constantly. Not people who are here for only a few weeks
or get a non OA from your home country and you won't Have to do the 800,000 start putting in 65 every month and your done use wise and tick funds for living overseas which shows on your bank as international transfer use BKB OR YELLOW bank They accept larger transfers.