First off congrats on the eggs and I hear what your saying as it is a very exciting time! When you candle your eggs you are looking to see if they are fertile... this easily done because a fertile egg will show redish/deep pink veins running through it. An egg that is not fertile will show no veins and appear to be just plain white.
Now an egg that is bad for whatever reason will appear to be deep orangish yellow and sickly looking when candled. If you wish to look at actuall eggs here is a link that has some very good pictures!
www.homestead.com/shilala/candling.html
I believe this website show chicken eggs but the pictures provide a good visual refrence as to what you could/should be looking for.
As for how often to candle? I am currently sitting on a clutch of 8 western hognose eggs and I have candled 2 times... once after the first 30 days and once since so my wife could see them. Other than misting and periodic checking I believe in not disturbing the eggs unless absoloutly needed.
My Email
Feel free to drop me a line if ya have any more questions. And I hope this helped answer your questions.
Charles
-----
I loathe people who keep dogs. They are cowards who haven't got the guts to bite people themselves.
August Strindberg (1849 - 1912), A Madman's Diary, 1895