As for the rules, I'm not aware of a nice single list of them. Does anyone else know of one?
Yes, there are GM's all around the world -- US, England, South Africa, Scandinavia, the Netherlands, Australia, to name a few. If you look in the upper right corner of the website, you'll notice that the site clock has AEST (Australian Eastern Standard Time). That's because we have so many Aussie players. And more than one Aussie GM, as I recall. I know I'm often wishing I was in Australian time so I could make more quests -- and I'm US Mountain time.
You'll find plenty of people to play with during your waking hours, don't worry.