I believe the safest option is adding your country. I had the same doubt, and from what I checked nobody that added their own country had issues, but from the ones that had the issue, all added something different than their own country.
I had a similar situation and added my country instead of what was written under the authority section ( other country) and it worked for me.
I did this because I saw some people getting rejected ( even tho they wrote what was written on their passport). It could depend on the embassy you are applying from.
Yes you can. And Koh Samui last time I did (a month ago) didn't ask for Tm30. I just brought passport and a photo. The copies and forms I got all there.
The immigration officer were telling to everyone to return before 29th Jan if they want the 60 days extension, even people with visa that runs out end of February. the suggestion you're giving to people to not go there to "hack" the system is based on what?