my name is Eyad from syria -- i study in shanghai

i have wife and daughter (7 years ) and son ( 8 months) . they live in turkey with residence permit.
they want to visit me . what is the conditions or formal papers that they must have it to take visa.
what about money in bank . they shall settle with me in house. how long time they can stay in china .
i finish mu study i july 2014.