Yes, you will be able to stay, but there is a good chance that that Non-B is annotated with your current employer, so you would not be able to use it for a new employer.
"So Phetchabun office is another one that requires 2 months of seasoned funds for an in-country initial Non-O visa based on retirement.", so that makes them and Jomtien so far?
NOT a visa, it is an Electronic Travel Authorization, totally different to a visa and is only required normally for visa exempt entries to whichever country.
If she wants to leave, she needs a re-entry permit, you can get at immigration or the international airport. 1000 baht for single, 3800 baht for multi.