On the attachment from Tod it says extendable once per stay, after 360 days must leave for at least one day and renter to reset for another 180+180 days, so in essence other than 1 day you can stay 360 days for 5 years. Understand about the TAX rules.
It says exit and re enter on the same visa, no mention of additional 10,000tb each time, I'm raising some questions with London embassy prior to application.
The 500,000tb is also questionable as it does not clarify in Thailand or home country.