kind of... technically you can apply for another 30 day extension which will be rejected and then you are given 7 days time to leave Thailand, so practically it's indeed a 7 day extension
afaik: a B visa (btw, that's not an extension) as an employee of a Thai company with a minimum capital of (not sure how many million) THB and 4 (fake?) Thai employees, in a job that is officially allowed for foreigners to do allows you to work in Thailand
yup, non-immigrant O visa + 3 years of retirement extensions (that's not a "retirement visa") + 3 million THB invested in Thailand should be enough (as far as I understand these facts)