Hm. Lessee. What I'll recommend is gaming sources you can borrow/buy:
1) You want both books in Mage: The Ascension's Dead Magic series, which are grab-bags of magical practices from different cultures for a game with much the same premise as yours.
Dead Magic covers Africa, Mesopotamia, Mesoamerica, Greece, the Etruscans and the Arctic Circle.
Dead Magic 2: Secrets and Survivors covers Polynesia, Australia, India, the Norse and European Shamanism.
You may also want to look at Dragons of the East, Mage's Asia supplement. The main thing you want there is the summaries for Asian religions, but you might also care for the Wu Lung, the game's Chinese magical group.
Mage gets the most airtime since, well, I wrote for the old game for 5 years (and incidentally, I have some stuff coming up for the new one, too). I know that line pretty well. I'm hesitant to recommend the Tradition books, since they do deliberately alter some real world concepts, but they are not without merit.
2) You want The Mysteries for Ars Magica, which is an incredible attempt to bolt on ideas from genuine Western magical traditions onto Ars' "fantasy hermetic" base.
3) You want GURPS Cabal, Ken Hite's update of Western Hermeticism into a modern conspiracy RPG.
You *don't* want Bonewits, who is extremely biased.
For general research, here are some pointers from somebody who has done what you are doing now:
1) Do not get ensnared by Chinese philosophy. For magic, you want Chinese folk religion. You want religious Daoism over philosophical Daoism.
2) Wicca is almost entirely unlike the practice of ancient polytheism and is, in fact, adapted from old Golden Dawn sources at its root. Look almost entirely at historical material instead. This is easy to find.
3) The summaries of texts of alchemy are generally more useful than the specifics. Same for hermeticism. You *do* want to specifically study the life of John Dee to contrast with modern hermeticism.
4) You *do* want to study Theosophy, which is one of the biggest influences on the modern occult -- and our understanding of religions, even. We're just starting to recover from their scholarship.
5) I will now shre the wierdest link I ever got looking for this stuff:
http://www.xeper.org/maquino/
Michael Aquino is the head of the Satanist splinter sect called the Temple of Set. This is his fanfic page.