"The school has asked me to work a one-month probation period and then they will assist with the documents for a b visa and work permit. I am currently on a tourist visa and I am very worried that I will get into trouble. Should I have the correct visa and work permit before starting the job?"
It's certainly not unusual. Billy Weaver had the following to say on the ajarn Facebook page - In my experience, it takes many schools that long to even get the paperwork together. They dont want to give you a work permit if you prove to not be the teacher they are looking for. so it takes them time. If you have any problems then you generally have immigration or whoever call the school. That's in my experience.