Non Immigrant Multiple Entry Ed Visa

I noticed the AUA in Bangkok will help full time Thai language students get an ED visa for the amount of time they wish to study full time at the school. Full time study is defined as 30 hours a week. (Assumably, other schools can do the same thing.)

I am unclear on the mechanics of this, so could the experts clarify my assumptions.

1. I tell the school how long I want to study with them. Say, one year.

2. School sends a supporting letter

3. I apply for a non-immigrant multiple entry ED visa, which is automatically good for one year

4. I leave Thailand every three months, and there is no need to report to immigration on this visa (or is there a need after the first three months?)

5. I can get an additional three months bringing the total to 15 months if I use the last entry just before the expiry of the visa (a little hazy on how this seeming loophole works)

So far, correct or no?

OK, a question.

If I decided to stop studying during the time period of the visa, or wished to take a one month holiday in the middle of the study period, would I be legally required to leave the country and stop using the visa? In other words, is the 30 hour per week full time study requirment enforced for every week in Thailand?