No, there is no limit on either work permits or the number of non-B visas you can have.  There is only a limit (officially) on the number of teaching licence waivers, but many teachers have managed to work for years using these waivers. 

There will probably come a time when your employer needs to show your original passport as part of the visa / work permit process, etc and photocopies won't suffice.

If at all possible, ask if you can accompany the school staff on these processing trips. In other words, don't let your passport out of your sight.

There have certainly been instances of school admin staff losing passports and while it isn't the end of the world, it can be a real hassle and inconvenience to get a passport replaced.

Asking to accompany the school staff on a processing trip is certainly not an unreasonable request.  

"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.

I've asked around and no one has come up with a straight answer to this.

Someone did mention the minimum as possibly being 20 hours a week but the general concensus seems to be that there is no set figure. I'll update things when and if I hear something more concrete.  

You should ideally bring your original degree certificate and originals of any transcripts. And also a criminal background check if you can get one (although these seem to be less and less of a requirement as time goes by)

Don't fret about how many copies of each document you need to bring. It's not as though Thailand doesn't have photocopiers (as some people seem to think!)

This information comes from an ajarn reader.

It's common for schools to hang on to your teacher's license (both the permanent version and the version issued to that school for your current contract period) while you're working there.

Schools sometimes like to hang on to your passport and your blue work permit book too, officially for safekeeping, unofficially perhaps in an attempt to stop you disappearing at the end of the month.

Remember that your passport is yours, the school has no right to keep it and it should be kept with you.

The work permit has to be kept with you OR at your place of work during working hours: again the school has no automatic right to keep it in the school safe forever.

At the basic minimum, keep a copy of the work permit in case you need it to refer to the number or issue/expiry date.

When you leave your work, the school must give you your permanent teacher's license (but not the current one issued for your employment) whether you leave Thailand or remain to go on to a new job.

Check you have the original license with the original photograph and stamp on it. They have no right to keep the original permanent license and give you only a copy. It's yours, not theirs.

Don't overstay a visa in Thailand. It's as simple as that.

The overstay rules are getting stricter and stricter.

At best you will have to pay a fine depending on the number of days you have overstayed. At worst (if the overstay is a long one) you will be barred from entering the country for X number of years.

There's little point going into detail. DON'T OVERSTAY A THAI VISA. 

If you have a non-immigrant visa (possibly one that has been extended for a year) it will be cancelled if you leave Thailand.

So to avoid your visa being cancelled, get a re-entry permit from your local immigration office. 

This is very important if you have a work permit, because canceling your visa also cancels the work permit and you have to start the process all over again.

If you have a multiple entry non-immigrant visa which has been extended on a work permit (or you have a work permit application in process) then you still need a re-entry permit, because a new entry is considered to be a new visa, and everything will have been cancelled.

If in doubt, check with immigration first, because the consequences of getting it wrong are troublesome.

What should officially happen when a teacher quits a job and hands the work permit back to the employer is that both teacher and employer should go to the immigration department and inform the officer that the teacher has terminated his / her employment.

The officer will then cancel the teacher's visa and the teacher has 24 hours to leave the country. However there are many 'ifs' and 'buts'. If the teacher needs to organise transportation out of the country, etc, - as is often the case - they can ask the immigration officer for a 7-day visa extension (at a cost)

In reality, when many teachers quit their jobs, their employer simply can't be bothered to go and do the right thing at the immigration office and the teacher ends up staying in Thailand for the remaining period that their visa allows. 

This is something of a risky game to play because if you, the teacher, are stopped by police for a passport spot-check, you no longer have a work permit to support the visa in your passport.

My advice - do the right thing. Get a one-week extension and then leave the country.   

A consulate run is when you physically need to get a new Thai visa in your passport and that means schlepping to a Thai consulate/embassy in a neighboring country.

It goes without saying that consulate runs are more expensive, more time-consuming (and dare I say more stressful) than border hops.

Depending on what time of day you arrive, Thai embassies / consulates will issue you a new visa within 48 hours.