Look, Thailand isn't really a "mother may I" kind of country. Do your thing, don't draw attention to yourself and generally things will sort themselves out, especially with a little bit of tea money to the right people. Just keep your mouth shut.
Be aware though that if you are doing anything outside the perceived norm you are making yourself a target for extortion, both by locals and unfortunately other expats. That's why you keep your mouth shut about whatever it is you are trying to accomplish and make it legit sooner rather than later.
no, you can only extend once. Depending on where you are at you can then do a border run via an agency to get a fresh entry stamp in your passport to restart your clock.
In Pattaya for example a border run to Cambodia costs about 3500 baht per person and takes about 8 hours via a van.
If you aren't married you will have to apply separately - means you will both need your own separate accounts with the equivalent of 500k THB each in them.
Sure, they could do that or they could maintain the status quo of not asking anything. Individual immigration offices might also add on their own requirements for extensions asking for the same type of info. Or they may just smile, collect your baht and stamp an extension into your passport without verifying anything. As the saying goes, “This is Thailand” - consistency and logic don’t always apply.
