and make absolutely sure when you present your passport at the airport, to say this is on a reentry permit. Turn your passport to that page, even they will take it back to the first page. Look him/her straight in the eye, because often when they’re bored and tired and will start to automatically stamp you in for 30 days instead. check your passport stamp before you leave the area. 
If your girlfriend is applying for a tourist visa and she mentions you, a US citizen, having relationship with her, she absolutely won’t get the visa. The reason is that you could go together with her as a tourist, and the two of you could happen to decide to get married, and she would have the right to adjust status and get a green card. They don’t want that, they want you to get the fiancé visa and do consular processing. If she doesn’t speak of the relationship with you and says she’s going to tourist places, they’re unlikely to believe her. If she has the history of travel to other places, such as Europe, a house, car, and a long-term corporate or government job, she may have a chance. As someone else said, it sometimes take a second or third attempt, and it can take a year to get the interview.
Sometimes it’s not just for security, but they don’t want you logging in from overseas, because if you are out of your own country, they don’t want you to have the account or have additional restrictions.
you get the visa once and extend each year, but you have to maintain money in thai bank. My concern is they’ll raise required banked money, not the small fees to get or extend visa.
in the past they grandfathered existing visa holders to the previous amount in the bank. This is the current ฿800,000 in bank, not the ฿1900/year to extend the visa.
I do plan to keep my retirement visa if I leave, because if I want to move back, they may raise the amount you have to have on deposit to an amount I can’t afford.