Depends on what your extension of stay based on. If it's based on marriage or thai child you don't need to keep it in the bank once you have the extension. For retirement
that's exactly what I inferred. If the funds have only been in the bank for 2 months you still get the letter but the 800k baht is frozen for an additional 2 months. At least that's how I understand what is being said. No direct experience as this wasn't an issue when I did my extension last month
in other words it makes zero difference to a retirement extension as immigration requires you have the 800k funds in place for 2 months (3 in some places) before applying and keep it there for 3 after you receive the extension. The ones it will affect are those on a marriage extension
There is no rule governing the amount of time you can spend inside Thailand nor is there a rule governing how many times you can enter. It's entirely up to the immigration officer you will stand in front of, they can see your history and if it looks like you are not a typical tourist they are likely to deny entry