Are work permits issued on a local basis, for instance in Songkla or Bangkok or Chiang Rai ? Or is this being handled centrally in Bangkok by the MoE ?

Each province has a Employment Department that is part of the provincial ministry of labour that issues work permits. For teaching, your credentials will be submitted by the employment department to the provincial ministry of education for clearance. Unless your school is in Bangkok, your work permit will be issued by the province in which your school is located.

For teaching, your credentials will be submitted by the employment department to the provincial ministry of education for clearance.

In many provinces you have to submit the permission letter of the Education Service Area of the Ministry of Education when applying for a work permit (renewal).