Angela Snape's Asylum

I realize that most of my f-list is in the US, but not everyone is ... book one was HP and the Philosopher's Stone - except in the US, where it was changed to Sorcerer's Stone.

Which is canon? Does it matter?

Do all magical creatures/plants get capitalized, or just those that JKR made up? Or not even that??

According to the Harry Potter Lexicon, Dementor is capitalized, as is Doxy, but boggart & grindylow aren't? She capitalizes Muggle & Squib, but not wizard, because it isn't something she made up, right?

Is there another resource, besides the original books, that could help me??