On first submission I believe it only needs to be in the account (if its a lump sum based application) on the day of submission, for extensions you'll need seasoning for the required time.
There's a couple of ways to do it, as long as you meet the criteria for non-0 (retirement / >50yrs)
I converted my stay to a non-0 inside Thailand, giving me 90days, then apply for a year long extension toward the end of those 90 days, and then renew a extension annually.
As for costs I think its a standard 1,900 per submission/application.