in Australia 30% of first marriages fail. Of those that remarry 60% fail. Most men going to Thailand are either divorced at least once so there is probably a good chance that 60% or more will fail. That is not considering the cultural adjustment that many men can't make. I wouldn't be looking at the Thai woman as the primary cause of relationship failures.
We used a visa agent the first time to learn the ropes. Done several for ourselves since including for her sons. This is for Australia which is basically the same requirements. Give them everything on the list. Don't leave anything out. Even statutory declarations.
I'm in a house directly across the road from the temple. Mother in laws house. My mother in law also manages those markets for the monks. It is definitely a drop in house and only the MIL alco brother lives in the old shack down the back of the block. I built a granny flat attached to the main house (less outlay). We have a block outside the village to build our forever home away from all the noise and people.
It's an attempt to extort you to get your passport back. They will find many things wrong with the motorbike and charge you ridiculous amounts to get your passport back!