MOE exam for foreign students studying Thai

I would like information from those who have experience with the MOE exam, in particular:

1. When is it actually held? Some say 6 months, some say 8 months - and if held at 6 months, is it held just before your second 60/90 day extension?

2. Where is the exam conducted, by who and how long does it go for?

3. Anyone know how many people pass or fail on average?

Please only comment if you know, as I would prefer to hear from those with actual experience, rather then general assumptions.

Thanks