Yes, related to online scams and call centres mainly. They need mule accounts to transfer money through. One way they can then launder funds is to buy properties and rent them to tourists.
To extend in the country, you will have to show ongoing activities. Leaving and re-entering on a new 180 day stamp seems to be the way to go, as people are not being asked to show ongoing SP activity currently.
Have a look at the LTR if your husband is an engineer. Got to BOI in Bangkok and ask directly. Many agents do not have knowledge in all areas so will try to sell you what is most convenient for them.
Your ability to apply a 3rd time may be dependent if your immigration record has a note attached to it about the rejection. If no note then applying elsewhere probably OK. If a note attached it can only be removed by originating embassy. The way to find out about any "Note" is to have an agent with "Contacts" enquire for you.