that would be an O visa based on retirement I got mine in Thailand, orginally eight years ago came into Thailand on an OA Visa, my choice did extensions for five years and then switched to an O, too me and many others the OA is no longer a desirable option
You don't have to inform immigration when you are leaving the country, just don't forget to get a re-entry permit before you leave, 90 day reports only have to be done when spending 90 consecutive days in the country, the count will restart when you come back to Thailand
never touched the 800,000, and Immigration never questioned it, I have had 65,000 coming in for a few years. If I was someone that was switching over I would not touch the 800,000 until I received my extension using the 65,000 baht method.