It all depends on what time period you are looking for. The Byzantine empire lasted for a long time, if I remember correctly more than 1100 yrs.
The first Byzantine emporer was a major proponent of christianity and he built a lot of churches, The second emporer was a very religious pagan and tried to stamp out christianity with some success before he died.
For how much magic you should allow, in the early part of the empire, divine magic about, but at the later times in the empire, more psuedo-scientific magic would be best. Also Constantinople has had several religious icons in it's boudries for its entire exsitance that would work as great artifacts.
A good book to give you an overview of the history of Byzantine is A Short History of Byzantine by John Julius Norwich. It is about 500 pages, but does cover most of the major events and emporers of the Byzantine empire.