And that's why I love Eyewitness books. They're incredible informative and easy to get into, even if they're made for kids.
On European medieval standard fantasy setting: yes, it does get boring, which is why I started going through books on tribal societies, ancient China and Japan, and the Aztecs. For one, one of the kingdoms in the series I've created has a government structure based a little off of the Mayan during their "Classical" period. But even then, it's hard to get good information on lots of different non-exhausted societies until you go to Wikipedia. I was going to get a book on fantasy worldbuilding when I read through a review: basically the reason why so many European based fantasy worlds is because it's the most analyzed in terms of fantasy, like in the book I was going to buy. The reviewer was upset that the only African civilzation reviewed was the Ancient Egyptians; so what about the Kush or the Meriotes or Great Zimbawe? And very little on Polynesian societies (I'm lucky that my mom had lots of books on that subject from a vacation to Hawaii).
The writing thing is something I'm glad you went over. I've heard of something called a "book curse", which monks used to ward people from burning or destroying copied books. Very useful back then.
Last point: the Paollini religion with the multilation rites. I'm thinking that's his "tract" on religion overall, and that makes me sad. You have to understand why people do what they do, ritual-wise. Rituals and customs have to have a rhyme and reason to them, even if they seem strange or useless. From what I've read, when an animal was sacrificed to the gods in Ancient Greece/Rome/etc, the gristle and bones were burnt and the meat was alloted to the people in attendance. Seems like it was a way to supply meat to the populace to eat. In Mercedes Lackey's Joust, it's noted that the sacrificed animals are given to the dragons to eat, the sands are warmed by transporting the heat from houses and temples to the sands for the dragons to nest in. She puts some rhyme and reason into how the dragons are houses and fed, to add weight to the story's world.