...also about the grading of coins...
Don't trust ANACS or other grading system as an infallible tool for grading physical coins, expecially bitcoin (IMHO part of them are randomly graded...) .
Use your experience, your brain, your eyes to judge them.
You can learn a lot maybe buying this book (I'm not doing Advertising, I think it will be a good guide book):
https://bitcointalk.org/index.php?topic=1022071.0or searching information in physical goods/auctions posts