Hi Kiri,
If I understand your questions correctly, I believe, yes you can create a custom Material and Appearance library file to store the styles.
Regarding sharing the library with others, there are primarily two approaches. Some users put it on a shared network drive. Some users use Vault to manage the files so each user pulls down the library files from the Vault server. I personally think the latter will give you the better performance. In either case, make sure the files are locked and not subject to change. Otherwise, you will end up with multiple versions of libraries and you don't know which one is the right one.
Many thanks!
Johnson Shiue (johnson.shiue@autodesk.com)
Software Test Engineer