@Dean Robert Hebron: There are many language schools that are closed by the authorities every year because they do not comply with the regulations and offer ED-Visa online classes which is against the law! For an ED-VISA students have to attend classes. That's the fact!
If you come by airplane it shouldn't be a problem, but as mentioned before, it all depends on the mood of the Immigration officer. If you want to make it sure try to get a Tourist visa there.
But only for privately used rental properties. For business premises, either a 2-month rental deposit is usual or an extra payment (key money) for any installations, aircons, furniture etc.
If you are in doubt and don't know the landlord or the rental property, I would recommend only paying a month's rental deposit first and the rest when you move in. A reputable landlord will agree to this.
This is how I do with my rental properties, because I have nothing to hide.
However, my regular tenants pay everything in advance and then get cheaper rent in return. Win - win!
Don't try to do by yourself. Pay them, go to the beach and relax, let them do and it will be successful and you don't have a headache with all that paperwork shit.
Thais are not as dumb as you think. When you say: "I want to eat rice" but you pronounce the word "rice" like the word "mountain" or the word "white" (which all sounds similar), then they can guess what you meant.